Cesarean scar pregnancies can present a challenge to treating physician. Through careful evaluation by minimal tools such as ultrasound, proper diagnosis and appropriate surgical planning can be performed.
Ultimately, this will positively impact patient’s future fertility and or pregnancy desires.
Cesarean scar pregnancy (CSP) refers to a rare type of ectopic pregnancy where the fertilized egg implants itself and grows within the scar tissue of a previous Cesarean section.
It’s extremely rare, occurring in approximately 1 in 1,800 to 1 in 2,216 pregnancies among women with a history of Cesarean sections.
Exact causes are unclear, but it’s believed to result from the fertilized egg implanting in the myometrial scar tissue due to a defect or thinning of the uterine wall at the cesarean scar site.
CSP is a serious obstetric complication requiring early recognition and appropriate management to prevent potentially life-threatening outcomes.
What are the risks CS Scar Pregnancy?
Risks may include:
Placenta Accreta Spectrum Disorders
Impact on Future Fertility
Complications from Treatment
Emotional and Psychological Impact
Risk in Future Pregnancies
These risks underscore the importance of early detection and appropriate management of CSP to minimize potential harm to the patient. Women with a history of Cesarean deliveries should be closely monitored in subsequent pregnancies, particularly for signs of ectopic implantation.
Video Transcript: CS Scar Pregnancy, the Challenge, the Triumph
During the course of this video, we will review the diagnostic and treatment dilemmas surrounding caesarean scar pregnancy. Caesarean section is one of the most common major procedures performed worldwide. With the global rise of caesarean section delivery rate and advancement of diagnostic skills, caesarean section defects are often visualised on ultrasound.
Caesarean scar pregnancy can arise on the background of caesarean scar defects, also known as isthmoceles. To revise, multiple hypotheses describe the aetiology of isthmoceles which include cervical location of uterine incisions, incomplete closure of uterine wall, surgical activities that may induce adhesion formation, patient or comorbidity factors that can affect wound healing.
The incidence of caesarean scar pregnancies is variable. It is reported as one in 1,800 to one in 2,200 pregnancies. Those represent six to 9% of all ectopic pregnancies in women with prior caesarean section. Presentation is also variable, patient can be asymptomatic, present with early pregnancy symptoms such as per vaginal bleeding or lower abdominal pain. Or are diagnosed in advance pregnancy, generally with the morbidly adherent placenta spectra.
Diagnosis can be done through ultrasound or MRI. With the power of ultrasound, the general rules for a diagnosis of caesarean scar pregnancy include empty uterus, empty cervical canal, mass seen in the anterior part of uterine isthmus. Myometrium is noted to be absent or thinned, measuring less than 5 mm between the bladder and the gestational sac.
These two images from our patient clearly show the abnormal location of the gestational sac within the anterior portion of uterine isthmus. The fundus of the uterus is empty with clear endometrial line and the gestational sac is barely separated from the bladder by a thin myometrium.
In a recent publication by the European Society of Human Reproduction and Embryology, caesarean scar pregnancies can be divided based on ultrasound into two types. Type 1, also described as partial caesarean scar pregnancy, where the gestational sac is implanted anteriorly, close to the internal os invading the myometrium, but also partially protruding into the uterine cavity.
Those pregnancies often present themselves in advance gestation with morbidly adherent placenta spectra, locating the internal os can be difficult. The use of colour Doppler and the identification of the course of the uterine artery can better help in its identification.
Type 2, also described as complete caesarean scar pregnancy, where the gestational sac is completely implanted within the anterior myometrium close to the internal os without visible communication within the uterine cavity. Those pregnancies, if left untreated, can face risk of uterine rupture and catastrophic haemorrhage.
Counselling patients can present a challenge to treating physician. Early detection of caesarean scar pregnancy has a paramount clinical importance. Patients need to be advised on risks of the condition, along with management modalities which include potential benefits and risks.
We will review in brief a recent case of caesarean scar pregnancy we recently encountered at our facility. A 34-year-old G5 P2 plus 2, known to have two previous caesarean sections, she achieved pregnancy by induction of ovulation and timed intercourse. She presented with minimal spotting, without abdominal pain.
Ultrasound was ordered and an outlined presence of a viable pregnancy with a crown-rump length of eight weeks, with gestational sac extending outside uterus. Ultrasound performed by the MIS group that were consulted for the case, outlined presence of Type 2 complete caesarean scar pregnancy. The gestational sac was clearly bulging into the anterior portion of the uterus, onto the bladder.
An ultrasound sweep from side to side depicted the location of the pregnancy. In these videos, the sweep helped in identifying that the pregnancy wasn’t centrally located within the scar, but rather more involving the right aspect of the scar. The use of colour Doppler can facilitate calculation of actual residual myometrial thickness and avoid overestimation. After thorough counselling and review, the patient consented for surgery.
She underwent transrectal ultrasound-guided aspiration and curettage, laparoscopic isthmocele repair, hysteroscopy and cystoscopy. We elected to commence the surgery with internal iliac artery ligation to decrease the potential risk of blood loss. The ureters were identified bilaterally, and careful dissection of the retroperitoneal anatomy was performed. Through identification of important anatomical landmarks, the right internal iliac artery was ligated with vascular clips.
Bladder dissection was initiated by opening the anterior leaflet of the broad ligament bilaterally, which aided into lower dissection of the bladder. It was clearly noted that the pregnancy was barely covered by any uterine serosa with complete loss of the myometrium overlying it. Aspiration and curettage was done under laparoscopic and transrectal ultrasound guidance. This was followed by a resection of the caesarean scar defect and repair in multilayer fashion.
The patient tolerated the procedure well, she was discharged home the following day. The patient had an ultrasound during her post-operative visit, it was clearly noted that the residual myometrial thickness had markedly improved from what was identified during her surgery.
Our patient’s journey doesn’t end with the completion of surgery, one should recognise the psychological impact of pregnancy loss. As a result, appropriate support should be provided. Let’s continue to educate ourselves for the importance of ultrasound in early detection of abnormally situated pregnancies. As this will impact counselling and treatment plans specifically tailored to our patients to provide the best results for their future fertility and or pregnancy desires.