Keywords
acute lower abdominal pain - gynecological imaging - pelvic emergencies
Introduction
Women with acute lower abdominal or pelvic pain frequently visit emergency rooms,
presenting diagnostic challenges for gynecologists and surgeons. The causes can be
gynecological, urological, or gastrointestinal, and management may range from conservative
treatment to emergency surgery. Accurate diagnosis is crucial for effective treatment,
often relying on imaging techniques.[1]
[2] An ultrasonography (USG) is the initial investigation of choice, while CT is used
for suspected urological or gastrointestinal issues. MRI is typically not performed
in emergencies, but it serves as a valuable problem-solving tool for gynecological
cases. This article offers a comprehensive review of female pelvic emergencies.
History and Clinical Examination
History and Clinical Examination
A thorough patient history is essential for diagnosing acute pelvic pain, beginning
with confirmation or exclusion of pregnancy. Key details include the last menstrual
period, cycle regularity, and symptoms such as bleeding or known fibroids. Assessing
pain characteristics and risk factors, including a history of ectopic pregnancy, pelvic
inflammatory disease (PID), or intrauterine device use, helps narrow down potential
diagnoses.[3]
A structured clinical examination is crucial alongside the patient's history. Vital
signs can indicate hemodynamic instability. Abdominal palpation assesses tenderness
and guarding, while a speculum and bimanual exam visualize the cervix and vagina,
allowing for detection of bleeding sources, uterine abnormalities, and adnexal masses.
Findings may indicate conditions like PID or endometriosis.[3]
Investigations
Laboratory tests are vital for initial evaluation. A pregnancy test is mandatory for
women of reproductive age with pelvic pain to rule out ectopic pregnancy. A complete
blood count (CBC) assesses for anemia due to blood loss from conditions like ectopic
pregnancy. In contrast, an elevated white blood cell count and C-reactive protein
can suggest inflammatory or infectious issues.[3]
The Importance of a Multidisciplinary and Imaging-Guided Approach
The Importance of a Multidisciplinary and Imaging-Guided Approach
In emergency settings, triaging patients with lower abdominal pain requires distinguishing
between surgical and gynecologic causes. A thorough history, physical examination,
and investigations are essential, but imaging is crucial for confirming or refining
the differential diagnosis by providing precise localization or etiology.[3]
[4]
Imaging Modalities: Choosing the Right Modality
Imaging Modalities: Choosing the Right Modality
USG is the primary imaging method for suspected gynecologic or obstetric causes of
pelvic pain. Transvaginal ultrasound provides excellent visualization of the uterus
and adnexa, is noninvasive, and uses no ionizing radiation. Color Doppler imaging
enhances diagnostic accuracy for assessing blood flow, particularly in cases of ovarian
torsion. Still, it can be limited in obese patients and when structures are outside
the viewing field.[3]
Multidetector computed tomography (CT) is commonly used in emergency settings, especially
for gastrointestinal or urinary tract issues, as it is fast, reliable, and readily
available when ultrasound results are inconclusive.[3]
[4]
Magnetic resonance imaging (MRI) is less frequently employed in emergencies but offers
superior soft-tissue contrast and is valuable for cases involving pregnant women and
young patients. It excels at diagnosing conditions such as endometriosis, adnexal
torsion, complex hemorrhagic cysts, PID, or degenerating fibroids when ultrasound
findings are inconclusive.[3]
[4]
The differential diagnosis of causes of acute pelvic pain in women encompasses a range
of conditions, from physiological processes to life-threatening emergencies, as detailed
in [Table 1].
Table 1
Differential diagnosis of gynecological causes of acute pelvic pain
|
Adnexal pathologies:
1. Ectopic pregnancy
2. Adnexal torsion
3. Pelvic inflammatory disease
4. Ovarian hyperstimulation syndrome (OHSS)
5. Corpus luteal cyst/hemorrhagic cyst/dermoid cyst rupture
6. Endometriosis
|
|
Uterine conditions:
1. Fibroid
2. Hematometra and pyometra
3. Uterine rupture
4. Vascular lesions such as pseudoaneurysms or arteriovenous fistulas with bleeding
|
This review emphasizes key imaging features of acute gynecologic emergencies to enhance
diagnostic accuracy and support timely clinical management. By integrating imaging
with clinical findings, we aim to improve radiologists' confidence in identifying
critical pelvic pathologies that may be initially missed. Our goal is to promote a
comprehensive, patient-centered approach to imaging, thereby facilitating accurate
diagnoses and timely interventions that lead to improved patient outcomes.
Ectopic Pregnancy
Ectopic pregnancy occurs when a blastocyst implants outside the endometrial cavity,
accounting for 2% of pregnancies and 18% of first-trimester bleeding cases.[5] In India, the incidence ranges from 0.9 to 2.3%. The classic symptoms include missed
period, abdominal pain, and per-vaginal bleeding, with risk factors including tubal
surgery, PID, intrauterine contraceptive device (IUCD) use, in vitro fertilization,
and congenital uterine anomalies.[6] The initial evaluation involves measuring serum β-hCG levels and performing an ultrasound,
preferably transvaginal sonography (TVS). A β-hCG increase of less than 50% over 48 hours
suggests a nonviable pregnancy, while plateauing levels indicate ectopic pregnancy.[7]
[8]
The fallopian tube is the most common site, with 95% of cases occurring there, primarily
in the ampulla.[9] Ultrasound findings typically show a heterogeneous adnexal mass without an identifiable
gestational sac. Specific signs include the tubal ring sign, indicating a thick echogenic
rim, and peripheral hypervascularity referred to as the “ring of fire.”[10] However, this can also be seen in a maturing ovarian follicle or corpus luteum cyst
([Table 2]). Early identification and management of ectopic pregnancies are essential to reduce
maternal mortality. Signs of a ruptured ectopic pregnancy include free fluid in the
pelvis and hematosalpinx.
Table 2
Differentiating features between ectopic pregnancy and corpus luteal cyst
|
Differentiating features
|
Ectopic pregnancy
|
Corpus luteum
|
|
Clinical scenario
|
A serious condition requiring immediate medical attention, especially in women of
childbearing age
|
Common in women of childbearing age, especially during pregnancy
|
|
Serum hCG
|
Elevated
|
Normal
|
|
USG
|
Appears as a well-defined, extraovarian cystic structure, often with a “tubal ring”
sign
|
Generally appears as a cystic structure within the ovary
|
|
Appearance
|
Presence of a distinct, extraovarian thick tubal ring. Hyperechoic (more than myometrium).
May show a gestational sac within
|
Absence of a distinct, extra-ovarian tubal ring.
May show a complex appearance with solid or cystic components and peripheral vascularity.
If present, hypoechoic, and a thinner ring
|
|
Doppler
|
May show higher resistance index (RI) values (>0.7)
|
Low impedance flow (nonspecific feature)
|
|
Indirect signs
|
Hemoperitoneum ++
|
+
|
|
Follow-up
|
Does not reduce in size without management
|
Reduces in size at follow-up
|
MRI, while not commonly used, can help pinpoint anatomical locations in challenging
diagnoses. A notable “three-ring sign” appears on T2W imaging, characterized by concentric
rings: an inner hypointense extraembryonic coelom, a hyperintense layer of fetal capillaries,
and an outer hypointense tubal wall, which displays restriction on DWI, indicating
the ring of fire sign. A heterogeneous mass, detached from the ovary, may indicate
a sealed ectopic pregnancy rupture ([Fig. 1]).
Fig. 1 A 31-year-old woman presented with acute abdominal pain, bleeding per vaginum after
8 weeks of amenorrhea. Urine pregnancy test shows a faintly positive result. (A) TAS shows a heterogeneously enhancing right adnexal mass (yellow arrow) without
any identifiable gestational sac. (B–D) MRI coronal and sagittal T2W imaging showing a heterogeneous right adnexal mass
with internal dark areas, separate from the uterus and both ovaries (yellow arrow).
Blood collection within the endometrial cavity (blue star). (E) Both right and left ovaries are seen separately from the mass (blue arrow). (F) Axial T1WI showing hyperintense areas within the mass, again suggesting right adnexal
mass with areas of variable stages of hemorrhage (yellow arrow and star). No evidence
of free fluid. Chronic sealed ruptured right adnexal ectopic pregnancy.
Interstitial pregnancies, rare at 2 to 4% of cases, involve implantation 1 to 2 cm
within the intramyometrial segment of the fallopian tube, with the gestational sac
(GS) separated by more than 1 cm from the uterine cavity edge.[11]
[12] The “interstitial line sign” is a thin bright line extending from the endometrium
to the GS and indicates interstitial pregnancy.[13] Cornual pregnancies show an empty uterine cavity and an eccentrically located GS
with minimal myometrial support(< 5 mm myometrial thickness), heightening rupture
concerns ([Fig. 2A–C]). Lastly, a pregnancy in a rudimentary horn is extremely rare (1 in 76,000) and
poses a significant risk of rupture and potential death[14] ([Fig. 2D–F]).
Fig. 2 (A–C) A 29-year-old woman presented with bleeding per vaginum after 7 weeks of amenorrhea.
Urine pregnancy test shows a positive result. (A, B) Axial T2W imaging showing a well-defined heterogeneous mass with internal hemorrhage
in the left uterine cornu (yellow arrow). The endometrial cavity shows only a thin
streak of blood products. Both ovaries are seen separately (green arrow). (C) Axial GRE image showing blood products within the mass (blue star) and endometrial
cavity (green star). Cornual ectopic pregnancy. (D–G) Another 33-year-old woman, 12 weeks of amenorrhea, with lower abdominal pain. UPT
positive. (D) TAS revealed a gestational sac with a viable fetus, crown-rump length of 5.6 cm,
over the left aspect of the uterus (yellow arrow). (E) MRI T2W imaging revealed that the sac was surrounded by a thin wall with the same
signal intensity as that of the myometrium (red arrow). (F, G) An ectopic pregnancy was assumed (blue star) with an empty uterine cavity (yellow
star). Laparotomy revealed a bicornuate uterus with a rudimentary horn pregnancy.
Implantation in the ovary accounts for 3% of cases,[15] detectable via USG, showing a GS with a “claw-sign” and a normal fallopian tube.
Cervical pregnancy, less than 1% of cases,[11] shows a classic hour-glass appearance on USG, with an enlarged cervical canal and
low-lying GS, distinguishable from threatened abortion through dynamic ultrasound.[16]
Blastocyst implantation over a previous caesarean section scar is very rare (< 1%)
but poses a high rupture risk. USG reveals a GS in the anterior inferior uterus with
myometrial thinning, while MRI helps in soft tissue evaluation[17] ([Fig. 3A–C]). This needs differentiation from cervical ectopic, low-implanted normal pregnancy,
and evolving pregnancy loss. ([Table 3])
Table 3
Differentiating features between scar ectopic and cervical pregnancy
|
Differentiating features
|
CS scar ectopic
|
Cervical ectopic
|
Low implanted normal pregnancy
|
Evolving pregnancy loss
|
|
Implantation site
|
Implantation above the os in the anterior myometrium. Os closed
|
Implantation below the os in the cervical canal
|
Implantation above the os in the endometrium
|
Contents may lie in the cervical canal, os open
|
|
Scar niche
|
CS scar niche not seen
|
Normal scar niche
|
Normal
|
Normal
|
|
Uterine lower segment anterior myometrium
|
Residual myometrial thickness <5 mm
|
Normal
|
Normal
|
Normal
|
Fig. 3 (A, B) TVS showing a large heterogeneous gestational sac (yellow arrow) in the myometrium
of the LUS with a developing embryo. The sac is abutting the anterior lip of the cervix
with thinning of the myometrium (yellow arrow). Sagittal T2W imaging showing irregular
heterogeneous GS embedded at the scar site with thinning of the overlying myometrium
and indentation over the posterior bladder wall (blue arrow), growth toward the endometrial
canal, and displacing the cervical canal posteriorly. (C) Follow-up USG after 1 week of medical management shows no significant vascularity
at the scar site, with substantial resolution. Scar ectopic pregnancy. (D–F) A 36-year-old woman, 22 weeks of amenorrhea, with abdominal pain. UPT positive.
T2W coronal and sagittal images show an empty uterine cavity (green arrow) with serosa
rupture and intraperitoneal location of the placenta and fetus. The myometrial vessels
are seen continuing with the extrauterine extension of the placenta (yellow arrow)—secondary
intra-abdominal pregnancy.
Primary intra-abdominal pregnancy occurs in the peritoneal cavity (1.4% of cases)
and typically goes undetected until the late second trimester. Secondary abdominal
pregnancy arises from initial implantation in the fallopian tube or uterus, followed
by rupture into the abdomen.[18] MRI provides better localization and assessment ([Fig. 3D–F]). Heterotopic pregnancy, a rare combination of intrauterine and ectopic pregnancy,
occurs in 1 in 30,000 pregnancies, but the incidence significantly rises with the
use of assisted reproduction techniques.[19] It may allow the continuation of the viable intrauterine pregnancy after careful
removal of the extrauterine pregnancy.[9]
Adnexal Torsion
Adnexal torsion is defined as the twisting of the ovary, and often of the fallopian
tube, on its vascular and ligamentous supports, resulting in venous followed by arterial
blood flow compromise leading to infarction. Ovarian enlargement increases the tendency
of the ovary to twist, and the presence of a benign ovarian lesion is the single most
significant risk factor. Other risk factors include ovulation induction, polycystic
ovaries, pregnancy, and prior pelvic surgery. Adhesions associated with malignancies
and endometriosis are thought to be protective.[20]
It is one of the common causes of acute pelvic pain in females.[21] Patients commonly present with an acute onset of severe pelvic pain localizing to
the side of torsion, nausea, and vomiting. Nausea and vomiting can be seen in up to
70% of patients with torsion. Early diagnosis of torsion is essential, along with
characterization of the associated ovarian lesion, if any, to avoid ovarian infarction
and subfertility and facilitate prompt and definitive surgical management.
Imaging Modalities
The initial imaging modality of choice is USG. In a systematic review, the diagnostic
accuracy of ultrasound was 79% compared with 42% for CT.[22] In patients with nonspecific symptoms, indeterminate adnexal masses, or equivocal
ultrasonographic findings, MRI is indicated, as it has the highest accuracy in diagnosing
torsion and characterizing associated ovarian lesions. In unsuspected cases of torsion,
CT may be performed to identify the cause of acute lower abdomen pain, which may raise
the suspicion of adnexal torsion by identifying ancillary features such as unilateral
ovarian enlargement, adnexal mass, free fluid, because only in a limited number of
cases the twisting of the pedicle is visible in CT.[23]
Imaging Findings
Key imaging findings observed in all the modalities include displacement of the enlarged
and edematous ovary towards the midline superior to the uterus, ovarian stromal oedema,
peripherally displaced follicles, and twisting of the thickened pedicle(identified
by “whirlpool” or “target” sign; [Fig. 4]).[20]
[24]
[25] Additional findings include the presence of a benign lead mass and pelvic free fluid.
While an enlarged ovary with or without mass is the most common finding, the pathognomonic
feature is twisting of the pedicle, and the latter can be assessed better with ultrasound
and MRI.[26] Due to poor soft tissue resolution, it may be challenging to establish twisting,
especially in noncontrast CTs.
Fig. 4 A 32-year-old woman presented with an acute onset of severe right-sided lower abdominal
pain for 1 day. Transvaginal ultrasound images revealed an enlarged right ovary with
diffuse stromal edema (measures with callipers in A and B). No internal vascularity is noted within the Doppler USG (C). Also, there is thickening and twisting of the right ovarian pedicle noted (white
arrow in D). Features suggestive of right ovarian torsion.
Ovarian viability can be assessed by Doppler USG and with contrast in CT and MRI.
The presence of arterial flow within the ovary does not exclude torsion, as the arterial
perfusion may be maintained until late in the course of torsion.
Absence of color flow or contrast enhancement is suggestive of ovarian infarction.
Additionally, a recent study suggested that even with a short MRI protocol featuring
limited T2 sequences, it is possible to establish a diagnosis of torsion and predict
ovarian viability by observing four T2 hypointensity signs: perifollicular, stromal,
capsular, and pedicle hypointensity. The presence of hypointensity is predictive of
necrosis ([Fig. 5]).[27]
Fig. 5 (A, B) A 40-year-old presented with an acute onset of severe right-sided lower abdominal
pain for 1 day. T2-weighted coronal MR images show an enlarged right ovary (black
star in A) with diffuse T2 hyperintensity—suggestive of stromal edema with thickening, twisting,
and hyperintensity of right ovarian pedicle (white arrow in B)—Features suggestive of right ovarian torsion. The ovary was viable during the surgery,
and laparoscopic oophoropexy was done. (C and D) A 39-year-old woman presented with an acute onset of severe left-sided abdominal
pain for 4 days. T2 sagittal MR images show an enlarged left ovary (white star in
C) with twisting of the pedicle (white arrow in D) and perifollicular, stromal, capsular, and pedicle T2 hypointensity. Laparoscopy
revealed torsion of the left ovary with necrosis. In histopathology, hemorrhagic infarction
was present.
Pelvic Inflammatory Disease
Pelvic Inflammatory Disease
PID is a common gynecological issue that often brings women to the emergency department,
with up to 70% of cases presenting there.[28] Symptoms can be mild and nonspecific, making diagnosis challenging. PID includes
infections of the upper genital tract, such as endometritis, salpingitis, and tubo-ovarian
abscess, typically caused by ascending infections from the lower tract, with Chlamydia
trachomatis and Neisseria gonorrhoeae being common culprits.[29] Less frequently, PID ([Fig. 6]) can result from hematogenous spread, notably in cases of tuberculosis in developing
countries. Common symptoms include pelvic pain, mild fever, vaginal discharge, and
dyspareunia, with risk factors including gynecological procedures, the use of an IUCD,
and multiple sexual partners.
Fig. 6 An 88-year-old woman with tuberculosis presented with fever and lower abdominal pain.
CT of the chest (A) shows centrilobular nodules in bilateral lungs, suggestive of endobronchial spread.
Contrast-enhanced axial CT image of pelvis (B) showing abnormal enhancement of the
endometrium and hyperemia of the inner myometrium (thick white arrow), indicating endometritis. (C) Loculated collection with thick enhancing walls in both adnexa (thin white arrows), suggesting tubo-ovarian abscess.
Endometritis
Endometritis refers to the inflammation of the endometrial lining, often seen after
gynecological procedures or in postpartum patients. Symptoms include pelvic pain and
vaginal discharge. Ultrasound may reveal a thick, echogenic, heterogeneous endometrium.
CT scans show a bulky uterus with heterogeneous enhancement at the endometrial-myometrial
junction and mild fluid in the endometrial cavity ([Fig. 7]). Acute cases may present with fat stranding in surrounding structures.[30] For postmenopausal patients, an endometrial biopsy is necessary to rule out malignancy.
Fig. 7 Endometritis in a 38-year-old woman presented with pelvic pain and vaginal discharge.
(A) Sagittal contrast-enhanced CT image shows a bulky uterus with hypodense thickened
endometrium (thick white arrow) with heterogeneous enhancement of the junctional zone. (B) Axial CT image shows a dilated fallopian tube with thick-wall enhancement (star). (C) Transabdominal ultrasound of the pelvis shows a bulky uterus with thick echogenic
endometrium (thin white arrow) and heterogeneous junctional zone. These findings are consistent with endometritis.
Salpingitis
Salpingitis is the inflammation of the fallopian tubes and is the most common acute
form of PID. In acute suppurative salpingitis, the tubal lumen fills with pus, leading
to pyosalpinx and possible surrounding peritoneal inflammation if untreated.[31] Chronic salpingitis involves persistent inflammation, resulting in adhesions, tubal
blockage, and infertility, and is a common cause of ectopic pregnancy.[32] Diagnosis relies on clinical presentation, as ultrasound may not be practical early
on, while CT scans can show thickened tubes (>5 mm) and fat stranding.[33]
[34] In cases of pyosalpinx, the tubes appear fluid-filled with thickened, enhanced walls.
Oophoritis
Sometimes infection extends from the fallopian tubes to the ovaries, resulting in
stromal swelling with surrounding oedema. On imaging, we can see enlarged ovaries
(greater than 3 cm) with increased vascularity. On the grey scale, it gives the appearance
of polycystic ovaries with multiple follicles and increased stromal vascularity.[35] On CT and MRI, it shows abnormal enhancement and mild free fluid in the cul-de-sac.
If it is unilateral, it should be differentiated from ovarian torsion, where the ovary
will be avascular. Isolated oophoritis is a rare condition that can be difficult to
diagnose.
Tubo-ovarian Abscess
Tubo-ovarian abscess is a serious complication of fallopian tube infection, occurring
in up to 15% of women with PID. It presents as a complex cystic solid mass.[36] On CT, it appears as a tubular cystic mass with septations and thick, uniform wall
enhancement, along with loss of fat planes and fluid in the cul-de-sac.[37] On MRI, it appears hypointense on T1-weighted images and hyperintense on T2-weighted
images, often exhibiting a hyperintense rim due to the presence of granulation tissue.[38]
[39] Differentiation from other pelvic abscesses is essential; for instance, endometriosis
can be distinguished on MR imaging due to its characteristic hyperintense signal on
T1-weighted images ([Fig. 8]).
Fig. 8 A 24-year-old woman with fever and lower quadrant pain. (A) T2-weighted image shows cystic lesions in the bilateral adnexa (thick white arrow), intermediate signal contents. (B) T1-weighted fat-saturated image shows hypointense
content with hyperintense rim in periphery (thin white arrow), suggestive of granulation tissue. (C, D) Contents show a prominent high signal on DWI with decreased ADC (white stars), indicating pus. (E, F) Fat-saturated contrast-enhanced T1-weighted coronal and axial images show thickening
and enhancement of the cyst wall (thick black arrows), which are indicative of tubo-ovarian abscess.
Fitz Hugh Curtis Syndrome
It is a chronic complication of PID where there is spread of infection into the perihepatic
space from the pelvis through peritoneal reflections. Imaging shows inflammatory changes
in the perihepatic region and pelvis with pyosalpinx or tubo-ovarian abscess.
Vulvar Abscess
Vulvar abscess commonly occurs secondary to infection of the Bartholin gland cyst,
and the less common causes include an infected epidermoid cyst. The Bartholin cyst
or abscess is located at the posterior third of the labia majora, posterolateral to
the vulva. When infected, it appears as a thick-walled cystic structure with internal
debris and surrounding inflammatory changes.
Ovarian Hyperstimulation Syndrome
Ovarian Hyperstimulation Syndrome
Ovarian hyperstimulation syndrome (OHSS) is a complication mainly associated with
assisted reproductive technologies (ART), particularly in vitro fertilization (IVF).
It occurs due to an exaggerated ovarian response to hormonal stimulation from exogenous
gonadotropins.[40]
[41]
OHSS is characterized by increased capillary permeability, triggered by vascular endothelial
growth factor (VEGF), which leads to fluid leakage and complications such as ascites
and pleural effusions. Risk factors include younger age, low BMI, polycystic ovarian
syndrome (PCOS), and a history of OHSS, with anti-Müllerian hormone (AMH) levels helping
to predict susceptibility.[41]
OHSS ranges from mild to severe, classified by the modified Golan system. USG is the
primary imaging modality for assessing ovarian hyperstimulation syndrome (OHSS), which
typically reveals enlarged ovaries with multiple peripheral follicles arranged in
a “spoke-wheel” pattern ([Fig. 9]). The presence of ascitic fluid indicates moderate disease. At the same time, severe
cases may present with pleural or pericardial effusions and ovarian diameters over
12 cm. Ultrasound also aids in guiding paracentesis for symptomatic ascites.[40]
[42]
Fig. 9 A 28-year-old woman undergoing ovarian stimulation who presented with bloating, nausea,
and mild abdominal pain. (A, B) Transvaginal grey-scale ultrasound shows the right and left ovarian enlargement,
multiple enlarged follicles, consistent with ovarian hyperstimulation. (C, D) There is mild free fluid in the intraperitoneal cavity.
CT and MRI are used for complex cases or inconclusive sonography, especially when
complications like pulmonary embolism are suspected. Complications may include ovarian
torsion, hemorrhage, thromboembolism, and, occasionally, abdominal compartment syndrome.[40]
[42]
While ovarian enlargement and multicystic morphology are common in ART cycles, differential
diagnoses should include polycystic ovarian morphology, theca lutein cysts, and ovarian
neoplasms, relying on imaging and clinical history for differentiation.
Spontaneous OHSS is very rare and linked to endogenous hormonal factors like β-hCG-secreting
tumors, pituitary adenomas, or hypothyroidism. Its radiologic features resemble those
of induced OHSS, including bilateral ovarian enlargement, multiple cysts, and ascites
or pleural effusion. Diagnostic imaging, particularly ultrasound, is vital when there
is no recent history of ovulation induction[43]
Hemorrhagic/Ruptured Corpus Luteum or Dermoid Cyst Rupture
Hemorrhagic/Ruptured Corpus Luteum or Dermoid Cyst Rupture
Ruptured or hemorrhagic ovarian corpus luteal cysts are a common cause of acute pelvic
pain in women of reproductive age.[1] The corpus luteum forms post-ovulation, secreting progesterone to support early
pregnancy. Fluid or blood released during ovulation can cause mild mid-cycle pain
known as Mittelschmerz, but larger amounts may lead women to seek emergency care.[44] A ruptured tubal ectopic gestation can mimic this condition, with elevated beta
HCG levels aiding in the distinction.
Ultrasound is the preferred method for identifying the corpus luteum as a cystic structure,
usually ≤3 cm, characterized by thick, crenated hypoechoic walls and internal echoes.
Color Doppler imaging reveals the “Ring of Fire,” indicating intense peripheral vascularity
([Fig. 10]). Associated fluid or hemoperitoneum may present as low-level echoes in the pouch
of Douglas and other areas. Occasionally, the corpus luteum can exceed 3 cm, exhibiting
internal hemorrhage with a fishnet pattern.[45]
Fig. 10 A 20-year-old woman presented with an acute onset of severe right-sided lower abdominal
pain. (A and B) Transvaginal ultrasound and Doppler images show a CL cyst in the right ovary (white
arrow in A) with peripheral vascularity and hematoma in the right adnexa (white star in A). CT plain (C) and post-contrast (D) images reveal a hyperdense hematoma in the pelvis (black star) with mild hemoperitoneum.
Also, CL cyst (white arrow in D) is redemonstrated in the right ovary. Her last menstrual period was 15 days ago,
and beta-HCG was negative. These features are consistent with a ruptured right ovarian
corpus luteal cyst with pelvic hematoma and hemoperitoneum.
CT scans can quickly identify the source of hemoperitoneum, showing hyperdense fluid
in the pelvic or abdominal cavity, with potential active bleeding from the corpus
luteum appearing as a hypodense structure with peripheral enhancement during the portal
venous phase ([Fig. 10]).[46] MRI is less standard for acute pelvic pain, but can incidentally reveal a hemorrhagic
corpus luteum as T1 hypointense and T2 hyperintense, with variable signal intensity
depending on blood age. CEMRI can assess dehiscence or rupture in a corpus luteum
cyst.[47]
Differentiating hemorrhagic corpus luteum from endometriotic cysts is essential, as
the latter shows distinct imaging features.[48] Hemodynamically stable patients can be managed conservatively with pain relief and
follow-up scans, while unstable patients may need laparoscopic drainage and cystectomy.[49]
Rupture of ovarian dermoid cyst is a rare(1-2%) but recognized complication. Patients
present with sudden onset, severe abdominal pain, and distension due to spillage of
cyst contents. On imaging, the presence of dermoid cysts in the adnexa, along with
fat stranding, peritoneal thickening, free-floating fat, and calcifications, will
be seen along with free fluid.[50]
Endometriosis
Endometriosis is an estrogen-dependent condition characterized by functional endometrial
tissue outside the uterus, affecting mainly women in their reproductive years. It
significantly contributes to pelvic pain and infertility. The exact cause is unclear,
but theories include retrograde menstruation and immunologic dysfunction. Risk factors
include early menarche, short and prolonged menstrual cycles, nulliparity, and a family
history of the disease.[51]
[52]
Transabdominal ultrasound is less sensitive than transvaginal ultrasound (TVS), which
is commonly the first imaging choice in suspected cases due to its accessibility and
ability to assess pelvic structures dynamically. MRI offers superior tissue contrast
and is especially useful for identifying endometriomas, fibrosis, and complex anatomical
distortions.
Endometriomas can present acutely, often in the context of PID, which is more severe
and resistant to antibiotics in individuals with endometriosis. Many cases occur after
assisted reproductive technologies (ART) within the first year. Imaging may reveal
salpingitis, oophoritis, pyosalpinx, and tubo-ovarian abscesses.[53]
The development of acute hematosalpinx can cause acute abdominal pain in patients
with endometriosis. On USG, it appears as a tubular cystic lesion in the adnexa with
homogeneous ground glass internal echoes ([Fig. 11]).
Fig. 11 A 35-year-old woman presented with acute lower abdominal pain. (A) Ultrasound showing a tubular cyst lesion with homogeneous internal echoes and multiple
small septae (marked by a white star)—suggestive of hematosalphinx. (B) Transvaginal ultrasound image shows heterogeneous myometrial echoes and cysts (annotated
in B) in subserosal location consistent with a solid invasive form of deep pelvic endometriosis.
Endometriomas are also prone to infections due to their impaired local immunity and
rich blood content. Infection routes include ascending infections from the genital
tract, hematogenous spread, and direct inoculation during procedures. Signs of infection
on imaging include increased wall thickness, low-attenuation cystic masses on CT scans,
and diffusion restriction on MRI.[52]
[53]
[54]
Though rare, the rupture of endometriotic cysts can lead to acute abdominal symptoms
similar to hemorrhagic ovarian cyst rupture. Imaging with ultrasound and CT may suggest
rupture, while MRI is the most specific. It shows loss of signal characteristics,
distorted cyst contours, and hemorrhagic ascites ([Fig. 12]).
Fig. 12 A 36-year-old female with a history of endometriosis cysts in the right ovary presented
with the acute onset of lower abdominal pain. On MRI, the pelvis axial T2W imaging
(A and B) and T1 FS (C) show an irregular, partially collapsed cyst (white arrow in A and C) with T2 hypointense and T1 hyperintense contents within. Free fluid with blood fluid
levels and T1 hyperintense contents are noted within the pouch of Douglas and peritoneal
cavity (black arrow in B and C). Also note the extensive inflammatory changes in the pelvis (white star in A and C). These features are consistent with rupture of an endometriotic cyst with hemoperitoneum
and reactive pelvic inflammatory changes.
Torsion of endometriomas is uncommon but may occur in cases of hematosalpinx. MRI
findings typically show high T1-weighted signals due to hemorrhagic content and a
lack of typical T2 shading in other endometriotic lesions.[53]
Differential diagnoses include hemorrhagic ovarian cysts, dermoid cysts, and mucinous
tumors. Hemorrhagic cysts typically have a lace-like internal pattern on ultrasound.
Dermoids show fat suppression and chemical shift artefacts. If an infection is suspected,
a tubo-ovarian abscess should be ruled out. In a ruptured corpus luteum cyst, hemoperitoneum
may appear as an intermediate signal on T1-weighted sequences, with a high-signal
clot present.
Acute Complications of Fibroids
Acute Complications of Fibroids
Fibroids are benign lesions of the myometrium and are the most common gynecological
neoplasms, with the incidence of up to 20 to 40% in women of reproductive age.[55] While many fibroids are asymptomatic and detected incidentally during pelvic imaging,
approximately 20 to 50% of women with fibroids will have symptoms such as abnormal
uterine bleeding and pelvic pain.[56] The pain due to fibroids is often chronic.
Very rarely, fibroids can cause acute symptoms and present as an acute abdomen. Acute
complications of fibroids include torsion of pedunculated subserosal fibroids, prolapse
of pedunculated submucosal fibroids, degeneration, spontaneous hemorrhage from fibroids,
and pyomyoma.
Ultrasound is the initial investigation of choice in patients presenting with gynecological
symptoms.[57] However, CT, although not an appropriate method for evaluating fibroids, is performed
as the initial investigation in some patients due to the clinical symptoms of an acute
abdomen.
In ultrasound, the fibroids appear as well-encapsulated heterogeneous masses with
dense posterior shadowing and predominant peripheral vascularity. While ultrasound
has high diagnostic accuracy in detecting fibroids, its role is limited in further
characterizing them and identifying associated complications.
MRI is the most accurate investigation to diagnose complications associated with fibroids
because of the better soft tissue contrast and ability to demonstrate enhancement
characteristics.[57]
Torsion of Pedunculated Subserosal Fibroid
Pedunculated subserosal fibroids with a narrow pedicle are prone to torsion and present
with the acute onset of lower abdominal pain, nausea, and vomiting. On imaging, the
diagnostic feature is a pedunculated subserosal fibroid with twisting of its pedicle
identified by a “whirlpool” or “swirl” sign. Due to a narrow pedicle, the diagnosis
of torsion is often challenging with ultrasound, and further imaging with CT or MRI
is required.[58] In the majority of cases, the fibroids show no blood flow on Doppler USG and no
enhancement on post-contrast MR images ([Fig. 13]). The close differential is a solid ovarian lesion with torsion.
Fig. 13 A 30-year-old nulliparous woman presented with an acute onset of severe lower abdominal
pain for 2 days. (A and B) Transabdominal ultrasonogram image shows a large subserosal fibroid with no internal
vascularity (white star). T2 sagittal (C) and T2 axial (D) MR images show a pedunculated
anterior subserosal fibroid (black star in C and D) with twisting of its narrow pedicle (marked by white arrow in D). On post-contrast images, it shows that the majority of the lesion is nonenhancing
(white star in E). Also note the surrounding inflammatory changes (black star in E). The findings are consistent with torsion of a pedunculated subserosal fibroid with
infarction.
Pedunculated subserosal fibroids with torsion are managed by emergency laparotomy
and excision.
Degeneration of Fibroid
Degeneration of the fibroid occurs when the fibroid outgrows its blood supply. Depending
on the degree of blood loss, the type of degeneration varies. The degeneration that
most commonly presents with acute symptoms is red degeneration. It commonly occurs
during pregnancy due to the thrombosis of the veins in the periphery of the lesion.
Diagnosis is based on the clinical symptoms and imaging characteristics. MRI is the
most accurate investigation to diagnose red degeneration. Fibroids with red degeneration
will appear hyperintense on T1 and T2 with no enhancement on post-contrast images[59] ([Fig. 14]).
Fig. 14 A 40-year-old lady presented with severe lower abdominal pain for 4 days. (A) Transabdominal ultrasonography image shows an intramural fibroid (black star in
A). MRI was done for further characterization. On MRI, the fibroid is predominantly
hyperintense on T2 and T1 (black star in B and C, respectively). On post-contrast T1 fat-saturated images, the fibroid shows a large
central nonenhancing area (black star in D) corresponding to T1 and T2 hyperintensity with minimal peripheral enhancement—suggestive
of red degeneration of fibroid.
Prolapse of Pedunculated Submucosal Fibroid
Prolapse of the pedunculated submucosal fibroid can present with an acute onset of
severe lower abdominal pain and heavy vaginal bleeding.
On ultrasound, the diagnostic feature is the presence of a heterogeneous polypoidal
soft tissue lesion with the endometrial cavity extending to the cervical canal and
into the vagina in some cases, with a vascular pedicle attached to the uterine wall
extending to the myometrium with focal disruption of the endometrial–myometrial junction.
Post-contrast MR images accurately demonstrate areas of necrosis if present. Treatment
usually consists of myomectomy or hysterectomy.[60]
Spontaneous Intraperitoneal Hemorrhage from a Fibroid
Spontaneous intraperitoneal hemorrhage from a fibroid is an infrequent, life-threatening
complication. It commonly occurs due to the spontaneous rupture of the subserosal
vein overlying the fibroid. Sudden increase in intra-abdominal pressure, as happens
during defecation or lifting heavy weights, is postulated to be a potential predisposing
factor.[61] Patients commonly present with an acute onset of severe lower abdominal pain, dizziness,
and features of hypovolemic shock. Imaging reveals a pelvic hematoma and a variable
amount of hemoperitoneum. However, it is difficult to ascertain the source of bleeding
in all cases.
The presence of hemoperitoneum and hemodynamic instability is an indication for emergency
laparotomy.[62]
Pyomyoma
Pyomyoma is an infrequent, life-threatening complication of a fibroid that occurs
due to infection of a necrotic focus within a fibroid. The predisposing factors include
post-pregnancy, post abortion, curettage, cervical stenosis, and immunodeficiency.[63] Typical clinical features include sepsis, leiomyoma, and absence of any other source
of infection. On USG, pyomyoma appears as a well-encapsulated lesion with echogenic
foci suggestive of air within. CT confirms the presence of air within the fibroid,
and MRI, it appears as a T2 hyperintense lesion with signal voids suggestive of air
within and peripheral rim enhancement ([Fig. 15]). A serious complication of pyomyoma is spontaneous rupture leading to peritonitis.
Early diagnosis and prompt management with antibiotics and myomectomy or hysterectomy
are essential to avoid mortality.[64]
Fig. 15 A 40-year-old nonpregnant woman presented with an acute onset of severe lower abdominal
pain for 4 days with no history of prior surgery/dilation or curettage. Transabdominal
ultrasound showed an area of air pockets within the myometrium with dirty posterior
shadowing (black star in A). Further evaluation with CT and MRI confirmed the intramural lesion with air pockets
within (white star in B and C, respectively), with surrounding inflammatory changes. Diagnosis: Spontaneous pyomyoma
of an intramural fibroid. Final HPE showed fibroid with infarction and multiple gram-positive
bacteria within—suggestive of pyomyoma.
Pyometra and Hematometra
Pyometra is a rare condition characterized by pus accumulation in the endometrial
cavity. It can result from obstructive cervical masses or cervical stenosis after
radiation therapy, endometritis, and secondary infection of retained products of conception
in postpartum patients.[65] Symptoms include whitish vaginal discharge, pelvic pain, and postmenopausal bleeding.
In severe cases, it can lead to uterine rupture and peritonitis ([Fig. 16]).
Fig. 16 A 25-year-old woman post-lower segment caesarean section day 9 presented with severe
abdominal pain. Reformatted contrast-enhanced CT scan sagittal image (A) shows an enlarged uterus with a thin imperceptible anterior uterine wall (thick white arrow). Coronal and axial images (B, C) show a distended uterine cavity filled with hypodense fluid (white stars) with a few air foci within. Hypodense ascitic fluid is also present (thin white arrow). Diagnosis of pyometra with uterine perforation was made, which was confirmed on
laparotomy.
Diagnosis typically involves an ultrasound, revealing a distended uterine cavity with
heterogeneous hyperechoic fluid. CT scans show hypodense fluid with parametrial fat
stranding, while MRI can highlight restricted diffusion and better assess the cervical
region.[66]
[67] Management consists of drainage, either vaginally or percutaneously, and patients
with ruptured pyometra require emergency surgery, including laparotomy and hysterectomy.
Hematometra is a rare cause of lower abdominal and pelvic pain due to blood accumulation
in the uterine cavity. In young adults, it often results from obstructed Müllerian
anomalies, while in older patients, it may be due to cervical stenosis from gynecological
procedures or malignancy.[68] Patients with Müllerian anomalies typically present with primary amenorrhea and
cyclical pain, while those with septate or bicornuate uteri may experience severe
dysmenorrhea ([Fig. 17]).
Fig. 17 A 17-year-old girl presented with severe dysmenorrhea T2-weighted sagittal and coronal
images. (A, B) Complete septate uterus with a distended left-sided uterine cavity due to obstruction
by a transverse vaginal septum (thick white arrows). Right-sided uterine cavity is usually communicating to the vagina (thin white arrow). T1W fat-saturated axial images (C, D) show hyperintense contents in the distended left uterine cavity, suggestive of blood
product (hematometra) (black star). Hyperintense contents are also seen in the dilated
left fallopian tube, suggestive of hematosalpinx (black arrow). Screening of the upper
abdomen revealed no renal anomalies.
Ultrasound reveals a homogeneous hypoechoic collection in the distended uterine cavity.
MRI is the preferred imaging method, showing a distended cavity with hyperintense
collections on T1-weighted images and detailed anatomy on T2-weighted images to assess
the type of anomaly and other causes[69]
Uterine Rupture
Iatrogenic gynecological emergencies arise from procedures involving the reproductive
system, such as dilatation and curettage or lower segment caesarean section. Early
identification and management are crucial to reduce maternal mortality. When using
ultrasound, a systematic outer-to-inner approach should be employed to assess the
scar site with a high-frequency probe.[17] While a few air foci are typical, a heterogeneous collection may indicate a hematoma
or abscess. Hematomas can appear hyperechoic in the acute phase and anechoic in the
chronic phase, making it essential to locate them for effective management.
Subcutaneous plane hematoma occurs at the scar site above the rectus abdominis muscle,
often involving the lower epigastric arteries. Rectus sheath hematoma forms within
the rectus abdominis muscle, while subfascial hematoma (SFH) is located just deep
to the rectus and superficial to the peritoneum. Bladder flap hematoma (BFH) occurs
between the bladder and lower uterine segment and is extraperitoneal ([Fig. 18]). A BFH greater than 5 cm can increase the risk of uterine dehiscence and may require
surgery, whereas one less than 4 cm is typically insignificant.[18] Long-standing hematomas can become infected, potentially leading to a loculated
pelvic abscess, characterized by symptoms such as fever and discharge of pus.
Fig. 18 A 38-year-old woman, 7 days post-lower segment caesarean section, with local site
pain and swelling. (A, B) Axial NCCT images show a hyperdense hematoma located in the space between the urinary
bladder and lower uterine segment (blue star), along with rectus sheath hematoma (red
star) (C, D). NCCT and (E) CECT sagittal images confirm the bladder flap (red arrow) and rectus sheath (yellow
arrow) hematomas.
Uterine dehiscence is the separation of the endometrium and myometrium with an intact
serosa. In contrast, uterine rupture involves a complete disruption of the wall, including
the serosa, resulting in a connection between the endometrial and peritoneal cavities.
Ultrasound shows a defect in the lower uterine segment (LUS) along with adjacent fluid
and hemoperitoneum. A continuous pathway between the endometrium and the extrauterine
collection, as seen on CT or MRI, is diagnostic ([Fig. 19]). The presence of gaps in the uterine defect suggests rupture. Dehiscence typically
requires conservative management, whereas rupture necessitates urgent surgery.
Fig. 19 A 32-year-old woman, day 8 post-lower segment caesarean section, with lower abdominal
pain, distension, and bleeding per vaginum. Axial and sagittal CECT images show a
defect in the LUS at the scar site (arrow) and adjacent collection (asterisk). Anterior
to the uterus and in the POD (blue arrow), uterine rupture.
Vascular Complications
Vascular complications in patients with vaginal bleeding may involve a uterine artery
pseudoaneurysm (UAP). A color Doppler can identify UAP by showing a yin-yang sign
(bidirectional flow). For anatomical details needed for urgent transcatheter angioembolization
([Fig. 20]), CT angiography is preferred. Rupture risk increases if the UAP diameter exceeds
2 cm.[70] Also, uterine arteriovenous fistula can occur after any intrauterine procedures,
presents with heavy bleeding, and requires angioembolization. [Table 4] summarizes the key clinical and imaging pointers for diagnosing common gynecological
emergencies.
Table 4
Key clinical and imaging pointers for diagnosing acute gynecological conditions
|
Acute gynecological emergency
|
Clinical presentation
|
Imaging findings
|
Key points for diagnosis
|
|
Ectopic pregnancy
|
Amenorrhea followed by irregular bleeding and acute abdominal pain
|
Heteroechoic adnexal lesion with pelvic hematoma, hemoperitoneum, and tubal ring sign
|
Elevated beta HCG levels
Absent intrauterine pregnancy and adnexal lesion
|
|
Ruptured corpus luteal cyst
|
Acute lower abdominal pain in the midcycle (ovulatory phase)
|
USG showing cystic lesion with thick crenated margins, with Doppler showing “Ring
of Fire” appearance, pelvic hematoma, and hemoperitoneum
|
Mid-cycle lower abdominal pain with imaging features of CL cyst and pelvic hematoma/hemoperitoneum
|
|
Adnexal torsion
|
Acute onset of unilateral lower abdominal pain is often associated with nausea and
vomiting
|
Enlarged ovary with stromal edema and thickening and twisting of the pedicle. Often
associated with benign lesions as a lead point. Absent vascularity
|
Acute unilateral lower abdominal pain with nausea and vomiting, with imaging showing
features of torsion.
Characterization of the associated lesion is crucial to plan the management
|
|
Pelvic inflammatory disease
|
Lower abdominal pain with systemic signs of infection
|
Diffuse smooth wall thickening of fallopian tubes with echogenic contents within -
suggestive of pyosalpinx and surrounding inflammatory changes and collections. In
MRI, smooth enhancement with wall thickening of the fallopian tubes with central restriction
in diffusion
|
Abdominal pain with systemic signs of infection and imaging showing inflammatory changes
in the pelvis with associated pyosalpinx and pelvic collections
|
|
Red degeneration of fibroids
|
Acute onset of lower abdominal pain in a patient with a fibroid.
Commonly seen in pregnancy
|
MRI is the most accurate modality to diagnose degeneration. On MRI, the fibroid will
appear hyperintense on T1 and T2 with no enhancement—suggestive of red degeneration
|
Common cause of lower abdominal pain in patients with fibroids complicating pregnancy.
Classical features of MRI help to establish the diagnosis
|
|
Torsion of a pedunculated subserosal fibroid
|
Acute onset of severe lower abdominal pain
|
Pedunculated subserosal fibroid with no internal vascularity. MRI better demonstrates
the twisting of the fibroid pedicle
|
Torsion of the fibroid should be suspected in patients with an acute onset of severe
lower abdominal pain with pedunculated subserosal fibroids with a narrow pedicle
|
|
Ovarian hyperstimulation syndrome (OHSS)
|
Seen in patients undergoing assisted reproductive technologies (ART). Patients present
with abdominal distension and bloating
|
USG revealed enlarged ovaries with multiple follicles arranged in a “spoke-wheel”
pattern. Severe cases will have ascites and pleural effusion
|
High index of suspicion for OHSS in patients undergoing ART helps in the prompt initiation
of treatment to avoid progression to severe disease
|
Fig. 20 A 26-year-old woman, 1.5 months post-lower segment caesarean section with vaginal
bleeding and anemia. (A, B) CECT demonstrates a focal contrast-filled outpouching at the left lateral aspect
of the uterus. The coronal MIP image illustrates the connection between this pseudoaneurysm
(arrow) and the left uterine artery (C, D). Pre- and post-transcatheter angioembolization show significant improvement. Left
uterine artery pseudoaneurysm.
Conclusion
When acute gynecological conditions are suspected, imaging findings must be interpreted
alongside the patient's clinical presentation. Key information, like the date of the
last menstrual period, is crucial for diagnosing many acute gynecological conditions.
Ultrasound is the initial imaging modality of choice for most gynecologic emergencies,
with MRI reserved for cases with inconclusive findings. Familiarity with clinical
presentations and imaging is essential for accurate diagnosis and optimal patient
care.
