Cesarean Section Complications
Karen Y. Oh, MD
DIFFERENTIAL DIAGNOSIS
Common
During Pregnancy
Placenta Accreta Spectrum
Dehiscence
Uterine Rupture
Postpartum
Bladder Flap Hematoma
Endometritis
Normal Cesarean Section Scar (Mimic)
Less Common
Uterine Rupture, Delayed
Cesarean Section Scar Ectopic
Endometrioma in Cesarean Section Scar
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
During pregnancy
Determine history of prior cesarean section (C-section)
Visualize lower uterine segment
Confirm hypoechoic myometrial layer present
Risk of rupture/dehiscence increases as lower uterine thickness decreases
Myometrium absent if uterine rupture/dehiscence has occurred
Document placental location
Placenta previa associated with accreta spectrum in 5% of cases
Take care to show preservation of subplacental hypoechoic zone if implantation on the C-section scar
Use Doppler liberally to assess for abnormal vascularity
Postpartum
Immediate postoperative complications often difficult to differentiate due to gas and edema in soft tissues from delivery
Healed C-section scar normally associated with focal mild thinning of myometrium
Helpful Clues for Common Diagnoses
Placenta Accreta Spectrum
Abnormal penetration of placental tissue beyond endometrial lining of uterus
Accreta: Attached to myometrium without muscular invasion
Increta: Chorionic villi invading myometrium
Percreta: Penetration of chorionic villi through uterine wall
Loss of subplacental hypoechoic zone
Should normally be present over entire placental surface
Hypoechoic zone may be difficult to see when placenta is anterior
Switch to high resolution transducer
Placenta previa present in almost all cases
Thinning of underlying myometrium ≤ 2 mm can be a sign of placental invasion
“Swiss cheese” placenta
Multiple hypoechoic placental vascular lacunae (“tornado-shaped” vessels)
Better positive predictive value than loss of subplacental hypoechoic zone
Interruption of bladder wall-uterine interface
Normal bladder mucosa is echogenic
Large vessels, or nodularity, extending through bladder wall can be seen with percreta
Dehiscence
Incomplete rupture: Disrupted myometrium but intact serosa
Loss of hypoechoic myometrial layer
Usually at site of prior C-section
In pregnancy, patient may be followed carefully to allow fetus to mature
Delivery indicated for any sudden pain
Reports of successful repair and continuation of pregnancy
MR may be helpful to assess for location and size of dehiscence
Uterine Rupture
Full thickness tear of uterine wall
May occur during pregnancy, labor, or puerperium
Highest risk in patients with history of C-section
Focal discontinuity of the myometrium at rupture site
Usually anterior lower uterine segment or site of prior myomectomy
Fetal parts and fluid in peritoneal cavity
During labor, imaging rarely performed as patient is emergently delivered operatively
Simultaneous maternal-fetal distress
Risk of rupture during spontaneous labor with prior C-section ≈ 5/1,000
In setting of trauma, CT useful → look for maternal solid organ injury also
Bladder Flap Hematoma
Hypoechoic clot at site of C-section on serosal surface
Between lower uterine segment and bladder wall
Endometritis
Most commonly occurs after delivery or termination
Associated with postpartum fever and pelvic pain
Endometrium may appear normal or have nonspecific findings
Thickened, heterogeneous endometrium
Echogenic foci of gas in endometrial cavity can be seen but also commonly related to delivery
Large amount of echogenic fluid concerning for pyometra
Retained products of conception (RPOC) is a risk factor
Sonographic appearance of RPOC overlaps with endometritis
Use Doppler to check for vascularity within endometrial contents
Normal Cesarean Section Scar (Mimic)
Focal triangular or wedge-shaped defect in myometrium
Anterior lower uterine segment
Small amount of fluid in scar is normal
Cystic-appearing C-section scar
May be confused with ectopic gestational sac in early pregnancy
Doppler ultrasound shows an avascular collection of fluid
Helpful Clues for Less Common Diagnoses
Uterine Rupture, Delayed
Postpartum full thickness tear of uterine wall
Following delivery, especially if patient had vaginal birth after prior C-section
Due to incompletely treated endometritis
After uterine instrumentation with a chronic healed scar
Myometrial defect can be seen with ultrasound, CT, or MR
If the patient presents with an acute abdomen, CT may be initial imaging modality to exclude other etiologies
Look for free intraperitoneal fluid or hemorrhage
Cesarean Section Scar Ectopic
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