Ultrasonic Evaluation of scar integrity Dr.Uma Gupta MD,FICMCH. Associate Professor,Dept of Obstetrics & Gynecology Era’s Lucknow Medical College.Lucknow umankgupta@yahoo.com Dr.N.K.Gupta,MS,M.Ch. Professor,Dept of Surgery,Era’s Lucknow Medical College.Lucknow. drnkgupta2000@yahoo.com

History Poidevin and bockner (1958) conducted a study and concluded that large wedge defects or sacculations in the anterior wall of the uterus measuring >5 mm in depth were indicative of ‘weak’ scars women with these findings were advised to undergo and elective repeat caesarean section (CS) in the subsequent pregnancy 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

History The advent of ultrasonography has revolutionized obstetric and gynaecologic practice, and has made hysterograms an obsolete test for imaging the uterine scar. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Advantages of Ultrasound Absence of irradiation Noninvasive nature Easy availability Low cost Feasibility of repeat tests. This being done in same patient have made it the most widely used test for imaging the uterine scar. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Increasing trends CS ↑ rates of CS -- Advances in perinatology Present day obstetricians have to care - large no of pregnant women with 1/more previous CS scars and women with the caesarean scar syndrome. Majority of the CS are LSCS; hence imaging for the uterine scar usually implies imaging of the anterior wall of the lower uterine segment (LUS). 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Beginning Donald first described use of USG during pregnancy to diagnose abnormal LSCS scars at risk for dehiscence as evidenced by an irregular or puckered appearance of the posterior wall of the bladder. Use of USG using the full bladder technique in immediate puerperium following a LSCS to diagnose haematoma in the scar Donald new problems in sonar diagnosis in obstetrics and gynecology. Am J Obstet Gynecol 118: 299, 1974. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Indication of imaging of the uterine scar Abnormal thinning, defects, asymptomatic dehiscence, imminent or incomplete rupture of the LUS or upper segment during the antepartum and intrapartum periods. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Indication of imaging of the uterine scar Haematoma /necrosis - dehiscence of: i) a recently sutured uterine incision in immediate postpartum period ii) uterine incisions in gynaecologic surgery like myomectomy or metroplastty. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Indication of imaging of the uterine scar Caesarean scar pregnancy. Endometrial polyps and blood clots in the uterine scar recess in women with previous LSCS presenting with abnormal uterine bleeding. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Monitoring Of the Scarred Uterus When? The best time to start monitoring is around 32 to 34 weeks. Sonography monitoring of the LUS before 28 weeks of pregnancy will not be very useful. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Monitoring Of the Scarred Uterus Why after 28 weeks? The length of the LUS is 0.5 cm at 20 weeks of gestation 1.0cm at 28 weeks 4.0 cm at 34 weeks 5 cm at 38 weeks and 5.5 cm at term Morrison J:. Aust NZ J obstet gynaecol 12: 182, 1972. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Monitoring Of the Scarred Uterus When? An isolated scan in labour is not recommended. Diagnosis of asymptomatic or symptomatic scar dehiscence can be determined. In unbooked patient, a scan in early labour, before rupture of the membranes can be useful 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

At What intervals patient with a previous ruptured scar be monitored ? At weekly intervals especially in month proceeding the time when previous rupture occurred successful diagnosis of imminent rupture and timely intervention. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Criteria To Diagnosis An Attenuated Weak Scar LUS wall thickness of <2 mm indicates poor healing -one with thickness of >3 mm indicates good healing.( Fukuda1988). LUS wall thickness of <5 mm as abnormally thin - Ballooning and abnormal movements of the LUS were indicative of an attenuated scar (Michaels 1988). Fukuda M, Fukuda K, Mochizuki M: Arch gynecol obstet 243: 221, 1988. Michaels WH, Thompson HO, boutt A et al: Obstet gynecol 71: 112, 1988 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Criteria To Diagnosis An Attenuated Weak Scar A wall thickness of ≤ 3mm to be a weak scar (Tanik et al 1996). Tank A, Ustun C, Cil E, Arsian A J Clin ultrasound 1996: 24:355-7 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Method of measurement Measured in millimeters on the LUS from interface of amniotic fluid and deciduas to the interphase of bladder and urine. A maximum of 4 measurements are taken and the average recorded. Further, LUS is studied for any areas of defects (thinnest area on lower segment) or discontinuations of lower segment wall. Posrtion between the two triangles is muscular layer of uterus Cheung VY. J Obstet Gynecol Can. 2005 Jul;27(7):674-81 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Scar Integrity testing manually after TOL The integrity of the scar is tested by performing intrauterine examination of the lower segment immediately following placental delivery in case of trial vaginal labour. Scar rupture is diagnosed when the hand is passed into the peritoneal cavity from uterine cavity. In case who underwent caesarean section the integrity of the scar was graded by direct observation as follows: 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Scar Integrity testing manually after TOL Grade 1 – no thinning of lower uterine segment Grade ll – thinning, dehiscence & rupture of the LUS Dehiscence is subperitoneal separations of uterine scar with chorioamniotic membrane visible through the peritoneum of lower segment. Rupture is a complete separation of uterine scar of any length resulting in communication between uterine and peritoneal cavities 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

The association between a lower uterine segment thickness and the integrity of lower segment was found by comparing the thickness in mm with grading in those cases who underwent caesarean section. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Studies (a) The risk of a defective scar was directly correlated to degree of thinning of LUS around 37 weeks of pregnancy. The high negative predictive value of the method may encourage obstetricians in hospitals where routine repeat elective cesarean is the standard procedure to offer a trial of labor to patients with a thickness value of 3.5 mm or greater. Rozenberg P, Goffinet F, Philippe HJ, Nisand I. J Gynecol Obstet Biol Reprod (Paris) 1997;26(5) 513-9. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Contd….Studies (a) Ultrasonography used to examine - scarred uterus in women - previous cesarean sections, at 36-38 weeks' gestation The overall frequency of defective scars was 4.0%. Frequency of defects -more as thickness of LUS decreased: no defects with LUS > 4.5 mm, 2% among 177 with values of 3.6-4.5 mm, 10% among 136 with values of 2.6-3.5 mm, and eight 16% among 51 women with values of 1.6-2.5 mm. With a cut-off value of 3.5 mm, the sensitivity of USG measurement was 88.0%, the specificity 73.2%, +ve predictive value 11.8%, and -ve predictive value 99.3%. Rozenberg P, Goffinet F, Philippe HJ, Nisand I. J Gynecol Obstet Biol Reprod (Paris) 1997;26(5) 513-9. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Studies(b) A prospective randomized study conducted to measure serial thickness of LUS by transvaginal ultrasonography in a control group of 80 women(no H/O uterine surgery) Study group of 43 women –H/O previous cesarean section Two mm or less as a criterion for poor healing had the sensitivity and specificity of 86.7% and 100% respectively. The positive predictive value was 100% and the negative predictive value was 86.7%. Qureshi B,Inafuku K, Oshima K, Masamoto H, Kanazawa K. Tohoku J Exp med. 1997; 183(1) 55-65. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Studies (c) Mean sonographic LUS thickness was 1.8 mm ± 1.1mm. An intraoperatively diagnosed paper-thin or dehisced LUS, when compared with an LUS of normal thickness, had a significantly smaller sonographic LUS measurement (0.9 mm ± 0.5 mm, vs. 2.0 mm ± 0.8 mm, respectively; P < 0.0001). Women had uterine dehiscence, both of whom had prenatal LUS thickness of < 1 mm. 31.4% had a successful vaginal delivery, with a mean LUS thickness of 1.9 ± 1.5 mm. A sonographic LUS thickness of 1.5 mm had sensitivity of 88.9%, a specificity of 59.5%, +ve predictive value of 32.0%, and -ve predictive value of 96.2% in predicting a paper-thin or dehisced LUS. Cheung VY. J Obstet Gynecol Can. 2005 Jul;27(7):674-81 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Clinical aspects and outcome 1.Important risk when a patient with previous caesarean section is subjected to vaginal delivery (is the uterine scar ruptured ?) Its incidence varies in various places. (occurs more frequently among those who were subjected to a trial). Uterine scar rupture occurred more frequently in induced labour. Visualizing the uterine scar prior to labour by non invasive methods i.e. USG 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

Conclusion Sonographic measurement of LUS is a valuable method for assessing the integrity of the scar to trial vaginal delivery. But however, the risk of scar rupture is increased with uterine stimulants even through the LST is >3 mm. 4/23/2017 Dr.U.Gupta, Dr.N.K.Gupta

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