Introduction. Cesarean Section US and CT of Acute and Chronic Complications. Overview. Acute Complications following Cesarean section

Introduction Cesarean Section US and CT of Acute and Chronic Complications Mindy M. Horrow, MD, FACR, FSRU, FAIUM Director of Body Imaging Albert Einstein Medical Center Associate Professor of Radiology Thomas Jefferson University

• Cesarean delivery accounts for approximately 1/3 of all births in the US. • Typical symptoms requiring acute post-operative imaging : fever with poor response to antibiotics over 2-3 days, dropping hemoglobin, unexpectedly heavy vaginal bleeding, pain. • Acute diagnoses include a variety of unusual hematomas, abscesses, wound infections and dehiscence, uterine rupture and pelvic thrombophlebitis. • Chronic findings include uterine adhesions resulting in difficult sonographic imaging. The C-section scar also may result in several rare, but unique diagnoses that are now made with increasing frequency.

Overview Acute Complications following Cesarean section

• “Normal” acute post C-section appearance: US and CT • Hematomas – Peritoneal: hemoperitoneum – Extraperitoneal: Bladder flap, subfascial, prevesical (space of Retzius) – Retroperitoneal

• Infections – – – –

Phlegmon and abscess Uterine dehiscence and rupture Superficial and deep incision infection and dehiscence Septic pelvic

• Other: ureteral and bowel injuries •

Four different “normal” studies

Choice of imaging modality: Depending upon the clinical situation, cost, availability and contraindications for intravenous contrast, one may use ultrasound, CT and/or MR. Our experience has been predominantly with ultrasound and CT.

CT and US in same patient with “normal” findings of small hematoma in myometrial incision

Staples in Pfannenstiel incision

Tiny focus of air in endometrium

Blood in endometrial canal Uterine incision

Small bladder flap hematoma

Myometrial sutures

Routine findings 4 days post C-section History: breech twins, abruptio placenta, post-operative fever not responding to antibiotics, probable endometritis

1. Uterine incision 2. Air in subcutaneous incision (air in bladder from Foley catheter) 3. Expanded endometrial canal with subacute blood (lochia)

Small myometrial and extrauterine hematomas

Normal CT Imaging post C-section

Normal US Imaging post C-section

• Obvious uterine discontinuity is common in the immediate postpartum period. • Other findings which are common and not clinically important include: small amounts of endometrial air and blood, small parametrial collections, and small bladder flap hematomas (< 2cm in thickness) • Our recommendations:

• Small, often linear, echogenic foci within uterine incision represent continuous sutures in myometrium. • Small indistinct mass-like region in incision representing a small hematoma is a common “normal” finding. • Small bladder flap hematomas are not uncommon. • Endometrial clot and debris and occasional foci of air are common findings with endometritis but also may be seen in normal healthy patients. • Our recommendation: Use a variety of frequencies and approaches to obtain optimal images: transabdominal (when the uterus is still large) and transvaginal or transperineal to visualize the lower uterus and the scar.

– If using CT for evaluation, intravenous contrast should be used if possible. – Best to image perpendicular to the plane of incision, using sagittal and coronal reconstructions.

Small bladder flap hematoma, hemoperitoneum

Infected bladder flap hematoma gas containing (echogenic foci) 5 x 6 x 7 cm collection History: Persistent pain and fever 9 days after C-section

Bladder

∗

∗ Classical transverse incision best visualized in sagittal plane

TA SAG

TA TRV

TV SAG

TV TRV

Bladder Flap Hematoma

Subfascial and abdominal wall hematomas

• A complication of a low uterine transverse incision. • The uterine incision is covered by a fold of peritoneum that is incised from myometrium and bladder • Bleeding from uterine incision is usually confined by overlying peritoneum, but can spread to broad ligaments, retroperitoneum and peritoneum. • Can be considered “normal” if less than 2-5 cm, and may occur in up to 50% • Surgical evacuation requires incision of peritoneum.

Infected rectus/subfascial hematoma Required surgical debridement

Bladder flap hematoma

Fever several days after C-section

Bladder

Subfascial Hematoma • Extraperitoneal hemorrhage from inferior epigastric vessels and their branches • Blood accumulates in prevesical space, posterior to rectus and transversalis muscles and anterior to peritoneum continuous with space of Retzius, potentially accommodating as much as 2.5 liters without a palpable mass. • May be evacuated without entering the peritoneum.

History: Premature rupture of membranes and chorioamnionitis

TA TRV

TA TRV

Uterine dehiscence Infected bladder flap hematoma Ileus

Uterine Dehiscence

Infection resolved with conservative management including antibiotics and catheter drainage

Re-admitted 12 days later for purulent drainage, progression to large bladder flap abscess, requiring hysterectomy

A

A

A

A

Follow up CT several days later

Ruptured uterus with broad ligament (B), extra- and retroperitoneal hematomas (H)

Uterine Dehiscence

Uterine incision

• Defined as infected and necrotic uterine incision with dehiscence at suture line, intact serosa. • Very difficult imaging diagnosis post C-section because of overlap with normal appearance of uterine incision. • Paucity of reports in the literature. Some claim that MR is preferred over CT because of multiplanar capabilities and better soft tissue contrast. • Presence of large (> 5cm) bladder flap hematoma may be related to underlying uterine dehiscence. • Difficult to differentiate partial from complete dehiscence. • Our recommendation is to look for gas in the uterine incision with possible extrauterine extension. Use sagittal and coronal reformatted images from multidetector CT.

Follow-up: Resolution of hematomas; tethered uterus Adhesion

SAG

Uterine incision B

B

H

Uterus

H

Uterine Rupture • Defined as complete muscular separation of myometrium • Accompanied by hemoperitoneum and/or other hematomas • High morbidity and mortality • Patients attempting vaginal delivery after csection (VBAC) at risk

Subcutaneous Wound Infection

Subcutaneous wound infection with dehiscence, small left rectus hematoma required drainage

∗

∗ Sub-acute blood in endometrium

Stat C-section for fetal distress with left extension, post-op fever unresponsive to antibiotics

Increased bleeding and persistent fever one week post C-section

Ruptured bladder flap abscess History: Fever, abdominal pain and free air on CXR, 2 weeks after routine C-section

Retained products of conception = focal enhancing endometrial “mass” Abscess

Extrauterine Infection • Extrauterine infections include infected hematomas, abscess and cellulitis. • Infection usually occurs in the region of incision, but can extend to the parametrium after cesarean section. • Frequency and severity of post partum infections are significantly greater after Cesarean section compared to vaginal delivery.

Bladder flap abscess contains gas (dotted arrow), associated with pneumoperitoneum (solid arrows), free fluid and infiltration of the omentum (dashed arrow).

Chorioamnionitis and failure to progress at 41 weeks gestation Dilated R ovarian vein with central thrombus and hyperenhancing wall IVC

Right ovarian vein septic thrombophlebitis Small focus retained products of conception

Unexplained post partum fever

Two different patients with diffuse septic pelvic vein thrombophlebitis RO Patient also had herniation of uterus at incision.

U UU

Thrombophlebitis - numerous veins with enhancing walls containing hypodense thrombus.

Septic Thrombophlebitis: Right Ovarian Vein

Ovarian and Pelvic Septic Thrombophlebitis

Pelvic pain one month post C-section

• 1/600 deliveries, though likely underestimated. • Usually unilateral, right more frequent than left. Right ovarian vein thrombus may extend to IVC. • CT and MR are techniques of choice. Sonography may be difficult due to bowel gas. • Findings include enlarged ovarian and other pelvic veins with low-density thrombus within the lumen surrounded by an enhancing vessel wall. Inflammation may be present in surrounding fat.

Obstructed uterus: Hematometros

Overview •

Chronic Complications following Cesarean Section

Normal scar : ultrasound and CT examples Complications of Cesarean scar:

• -

“Niche” Malpositioned IUD Ectopic pregnancy Placenta accreta Endometrial implant

Sonography and the Cesarean scar • In some patients, the scar causes significant distortion of the normal uterine position • When the cervix is elongated and the lower uterus is tethered to the anterior abdominal wall, transvaginal imaging allows excellent visualization of the cervix, but the corpus of the uterus is poorly demonstrated. • In this situation, transabdominal imaging is also limited, because the distended bladder will not serve as a “sonographic window” to the body of the uterus. • Our recommendation is to try a higher frequency curved transducer directly over the uterus, when the body habitus permits.

What is wrong with this uterus?

Adhesions of Cesarean section scar cause tethering of uterus, elongation of cervix

CT and simulated transvaginal view of a similar patient

US and CT views of tethered uterus: ovaries may also be pulled ventrally

Scar simulating a myoma

Endometrium may be pulled into the scar with thinning and irregularity of the overlying myometrium

Scar

SAG

Simulated myoma

COR

Blood can accumulate in the scar, causing inter-menstrual bleeding.

Retroflexed uterus with fluid in scar - CT and US

COR

SAG

COR

Blood in endometrial canal and scar SAG

Fluid in scar after miscarriage

History of heavy menses and inter-menstrual bleeding

M

SIS

Intracavitary myoma and prominent niche

IUD Malpositioned in Scar 2005 immediate post C-section

2006 IUD Malpositioned, partially in scar

The Cesarean Scar “pouch” or “niche” • Fluid may occasionally be present in scar during routine transvaginal scanning. • By filling the scar with fluid, sonohysterography can better delineate the defect and measure the depth. • Hysteroscopy correlates well with the findings on sonohysterography. • Routine hysterosalpingography can also demonstrate the scar. • The scar can act as a reservoir for blood and thus be a cause of abnormal bleeding. • What percentage of women with prior C-section will have a demonstrable “niche” is unknown.

TA/TV US confirms IUD partially in cervix, extending into scar

CT several days after C-section

Several months later patient is pregnant with bleeding

Cesarean Scar Ectopic Pregnancy

Two days later

SAG

COR

After treatment with systemic methotrexate, follow up study 5 days later showed growth of sac and cardiac activity. Second dose of methotrexate given.

Surgery Required

One month later returns with bleeding History Cesarean section x 1 Interpreted as abortion in progress

Ectopic Pregnancy in Cesarean Scar • A gestation completely surrounded by myometrium, but separated from endometrium and fallopian tube. • Several reports of occurrence within months of Cesarean delivery suggesting incomplete healing of scar may contribute to this ectopic implantation. • Probable mechanism is invasion of myometrium through a microscopic tract. Similar to interstitial pregnancy. • US Findings: empty uterine cavity, empty cervical canal, sac in anterior lower uterus

C-section scar implantation (ectopic) with retained products of conception

Ectopic Pregnancy in Cesarean Scar • Differential diagnosis: spontaneous abortion in progress and cervical ectopic. • Rupture can occur early and delayed diagnosis limits treatment options. • Because this type of ectopic pregnancy is so rare, no specific guidelines for treatment. Can try medical therapy, but only surgery will allow removal of the pregnancy and repair of the defect • Appears to be increasing in incidence • Distinctly different from placental implantation over the scar resulting in placenta accreta.

30 weeks pregnant with hematuria, history of Cesarean section

Placenta Percreta: Placental invasion of bladder Courtesy of Dr. Sandra Allison Georgetown University

Placenta Accreta • Accreta: villi in direct contact with myometrium without intervening decidua • Increta: deeper myometrial invasion • Percreta: invasion to serosa and sometimes to adjacent bladder and bowel • Risk factors: Cesarean section, instrumentation, placenta previa • Can result in life threatening hemorrhage at delivery because placenta will not separate from myometrium

Placenta Accreta • Modalities: ultrasound (TA, TV, with Doppler), MR (usually without gadolinium) – Sensitivities and specificities may be similar – With anterior placenta ultrasound is better – With posterior placenta MR is often better

• Criteria for suspecting placental invasion by ultrasound – Loss of retroplacental hypoechoic myometrial zone – Numerous vascular lacunae in placenta – Disruption of hyperechoic boundary between uterine serosa and bladder – Nodular projection beyond uterine edge

★Similarities between placenta accreta (myometrial invasion) and C-section scar ectopic (abnormal implantation site)★

Endometriosis in Scar - US

Endometriosis in Scar - CT Endometrial implant

History of increasingly painful C-section scar with mass

Adhesions

Endometrial implant is a nodular subcutaneous lesion in the Cesarean section scar with enhancement greater than adjacent muscles.

Incarcerated Ventral Hernia at site of scar

Endometrial Implant in Scar • Due to endometrial tissue spread outside of uterus during surgical procedure. • Symptoms include: pain and tenderness, worsening symptoms with menses, cyclic bleeding. • Variable appearance: cystic, mixed, solid; related to distribution of hemorrhagic and fibrotic material; often spiculated secondary to fibrosis. • Color Doppler frequently demonstrates dilated vessels. • Differential diagnosis: desmoid, mesenchymal tumors, hematoma. • Typically enhance dramatically with contrast.

History of 3 prior Cesarean Sections

References • • • • • •

Antonelli E, Morales A, et al. Sonographic detection of fluid collections and postoperative morbidity following Cesarean section and hysterectomy. U Obstet Gynecol 2004;23:388-392. Baker ME, Bowie JD, Killam AP. Sonography of post-cesarean-section bladder-flap hematoma. AJR 1985;144(4):757-9. Baker ME, Kay H, Mahony BS, Cooper CJ, Bowie JD. Sonography of the low transverse incision, cesarean section: A prospective study. Journal of Ultrasound Medicine 1988;7:389-393 Cheung VYT, Constaninescu OC, Ahluwalia BS. Sonographic evaluation of the lower uterine segment in patients wit previous cesarean delivery. Journal of Ultrasound Medicine 2004;23:1441-7. Fabres C, et al. The cesarean delivery scar pouch. Journal of Ultrasound Medicine 2003;22:695-700. Fylstra DL. Ectopic pregnancy within a cesarean scar: A review. Obstetrical and Gynecoloical Survey 2002; 57(8):537-43.

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Hamilton BE, Margin JA, Ventura SJ. Births: preliminary data for 2005. National Vital Statistics Reports 2007; 56(6):18-20.

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Hensen JH, Van Breda Vriesman AC, Puylaert JB. Abdominal wall endometriosis: clinical presentation and imaging features with emphasis on sonography. AJR 2006;186(3):616-20. Maldjian C, Milestone B, Schnall M, Smith R. MR appearance of uterine dehiscence in the post-cesarean section patient. Journal of Computer Assisted Tomography 1998;22:738-41.

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References (cont.) • • •

Wiener MD, Bowie JD, Baker ME, Kay HH. Sonography of subfascial hematoma after cesarean delivery. AJR 1987;148:907-10. Woo GM, et al. The pelvis after cesarean section and vaginal delivery: Normal MR findings. AJR 1993;161:1249-52. Zuckerman J, et al. Imaging of pelvic postpartum complications. AJR 1997;168:663-8.

References (cont.) •

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Monteagudo A, Carreno C, Timor-Tritsch IE. Saline infusion sonohysterography in nonpregnant women with previous cesarean delivery. Journal of Ultrasound Medicine 2001;20:1105-1115. Rivlin ME, Patel RB, Carroll CS, Morrison JC. Diagnostic imaging in uterine incisional necrosis/dehiscence complicating cesarean section. Journal of Reproductive Medicine 2005;50:928-932. Roberts JL, Madrazo BL. Ultrasound case of the day. Radiographics 1992;12:599601. Seow KM, Huang LW, Lin YH, Lin MY, Tsai YL, Hwang JL. Cesarean scar pregnancy: issues in management. Ultrasound Obstet Gynecol 2004;23(3):247-53. Silver RM, et al. Maternal morbidity associated with multiple repeat cesarean deliveries. Obstet Gynecol 2006;107(6):1226-32. Thurmond AS, Harvey WJ, Smith SA. Cesarean section scar as a cause of abnormal vaginal bleeding: Diagnosis by sonohysterography. Journal of Ultrasound Medicine 1999;18:13-16. Twickler DM, et al. Imaging of puerperal septic thrombophlebitis: prospective comparison of MR imaging, CT, and sonography. AJR 1997;169(4):1039-43. Twickler DM, Setiawan AT, Harrell RS, Brown CEL. CT appearance of the pelvis after cesarean section. AJR 1991;156:523-6.