Transient Distention of Right Posterior Located Sigma, a New Sonographic Sign for the Prenatal Diagnosis of Anal Atresia

First trimester lower abdominal cysts as early predictor of anorectal malformations

INTRODUCTION

Prenatal ultrasound diagnosis of anorectal malformations (ARMs) is challenging and often missed as direct visualization of the anal sphincter is not routinely performed, plus the technique is operator-dependent and inaccurate, also in expert hands. Other indirect signs, such as rectosigmoid overdistension or intraluminal calcifications, are occasionally present in late pregnancy. The detection of a cyst of the lower abdomen in the first trimester may be an early sign of ARM. Here we reported our experience and a review of the literature of such cases.

MATERIAL AND METHODS

Isolated cases of lower abdomen cysts encountered in the first trimester at the Prenatal Diagnosis Unit during the last 5 years were retrieved and compared with those found in literature. Post-natal clinical data were analyzed to check the presence and type of malformations.

RESULTS

A total of three cases of lower abdomen cysts were found in our center and 13 in literature. In our case series all the cysts spontaneously regressed and were no longer visible since the second trimester of pregnancy, while in literature this was reported in only 4 out of 13 cases. ARM was confirmed in all patients at birth or post-mortem.

CONCLUSIONS

The finding of a lower abdomen cyst during the first trimester of pregnancy could be an early predictive sign of ARM, even if it disappears during pregnancy. In these cases, we suggest mentioning to the parents the possibility of an ARM during the counseling and to refer the couple to a Colorectal Center.

Transient fetal hypertrichosis - Three cases

We Summarize a three cases of transient fetal hypertrichosis in low risk preganant women. Hypertrichosis has been previously associated with over 140 different syndromes (OMIM); however this finding is rarely described in prenatal ultrasound. In this study we describe the finding of hypertrichosis which resolved later in gestation. CASE N1: A prominent unibrow (synophrys) and elongated eyelashes were noted at 24 weeks of gestation with no other abnormal features. CASE N 2: A prenatal ultrasound scan was performed at 24 weeks and revealed: horseshoe kidney and localized hypertrichosis on the lower back. CASE N 3: Ultrasound exam at 24 weeks of gestation demonstrated localized hypertrichosis on the chin. CONCLUSION: Transient localized hypertrichosis with no other major findings has a favorable prenatal outcome.

Can Anorectal Atresia Be Diagnosed in the First Trimester of Pregnancy? A Systematic Literature Review

Anorectal atresia (ARA) is a common congenital anomaly, but prenatal diagnosis is difficult, late, and unspecific. Utilizing a case of a 46 year old primipara with an egg donation In Vitro Fertilization (IVF) pregnancy, diagnosed at the first trimester scan with an anechoic isolated structure, which indicates anal atresia, we performed a systematic literature review in order to evaluate early prenatal ARA diagnosis. A total of 16 cases were reported as first trimester ARA suspicion, and only three had no associated anomalies. The most frequent ultrasound (US) sign was the presence of a cystic, anechoic pelvic structure of mainly tubular shape, or a plain abdominal cyst. In the majority of cases, structures were thin-walled and delimitated from the bladder. The presence of hyperechoic spots signifying enterolithiasis and peristaltic movements were helpful in order to establish the bowel origin of the lesion. Considering the high eventuality that the lesion is transitory, meaning later in pregnancy the fetus looks normal, early detection of such a sign should prompt further structural detailed evaluation, karyotyping, and appropriate pregnancy and postnatal counselling.

Imaging of anorectal malformations in utero

PURPOSE

To document the imaging findings suggestive of anorectal malformation (ARMs) on prenatal US and MRI.

METHODS

Retrospective evaluation of the screening US and prenatal MRI exams of the rectum and ano-perineal region in normal fetuses and in patients with ARMs.

RESULTS

Examples showing the normal rectal and anoperineal anatomy on prenatal US and MRI exams and the imaging findings observed in different types of confirmed ARMS.

CONCLUSIONS

Prenatal diagnosis of ARMs requires both a systematic evaluation of the fetal pelvis and perineum and an appropriate knowledge of its suggestive imaging findings.

Prenatal imaging of anorectal malformations - 10-year experience at a tertiary center in Switzerland

BACKGROUND

Anorectal malformation is a spectrum of congenital defects of the distal bowel, mostly diagnosed at birth.

OBJECTIVE

To describe the prenatal imaging findings of anorectal malformations, explore the causes of the low rates of prenatal diagnosis, compare the accuracy of prenatal ultrasound (US) and magnetic resonnance imaging [MRI] and evaluate the relevance of information obtained at MRI.

MATERIALS AND METHODS

Children treated for anorectal malformation at our hospital and with available prenatal studies were retrospectively identified and included in the study. We reviewed prenatal imaging exams, listed findings suggestive of the diagnosis, and compared results with the final classification.

RESULTS

Fourteen fetuses and neonates - eight with intermediate-high type anorectal malformation and six with cloacae - fulfilled the inclusion criteria. All had associated congenital anomalies. Prenatal exams included 13 US and 8 MRI exams, with 7 children having both exams. Suggestive findings for anorectal malformation were detected in 50% of the cases prenatally and in 85% upon review. They were prospectively detected in 31% and 50% of the cases at US and MRI and retrospectively in 62% and 100% at US and MRI, respectively. MRI was superior to US because it improved the diagnosis, especially in cloacae, and provided relevant additional information that changed management in two cases.

CONCLUSION

The most important signs suggesting anorectal malformation are an absent target sign and anomalous distal bowel wall and rectal fluid. Complementary prenatal MRI improves the diagnosis of anorectal malformation.

Prenatal Evaluation for Detection of Anorectal Atresia: Value of Ultrasound

OBJECTIVES

To investigate the applicability and value of ultrasound (US) in the diagnosis of anorectal atresia.

METHODS

Between January 2008 and January 2016, we prospectively evaluated 63,101 fetuses (gestational age, 20-38 weeks), including low- and high-risk populations using 2-dimensional US scans. An abnormal imaging finding was defined as an anal canal diameter of less than the 95% confidence interval (small anal canal) of the normal range or the absence of an anal canal and rectum. Imaging findings were considered normal on detection of an anal canal with a normal width and the absence of abnormalities. Prenatal imaging findings were confirmed by a postnatal or postmortem examination.

RESULTS

Among the investigated fetuses, 28 showed evidence of anorectal atresia on US scans, and 22 of those with anorectal atresia had additional anomalies. Six cases of isolated anorectal atresia were successfully detected during the preclusive prenatal US scans. Four cases of a low imperforate anus (including 2 covered anuses) yielded false-negative results, indicating a diagnostic rate of 87.5% (28 of 32). The normal appearance of the fetal rectum and anal canal ruled out anorectal atresia in 30 fetuses with a dilated colon. Additionally, there were 3 false-positive cases, in which a narrow anal canal was observed.

CONCLUSIONS

Identifying the abnormal appearance or absence of the fetal anal canal and rectum on preclusive US anomaly scans is useful for prenatal diagnosis or exclusion of anorectal atresia, which may help improve the detection of isolated anorectal atresia. Furthermore, a combined evaluation of the longitudinal and axial appearances of the fetal anal canal and rectum can improve diagnostic accuracy.

First trimester expression of anorectal malformation: Case report and review of the literature

A 26-years-old woman, underwent an ultrasound examination at 13.4 weeks. A cystic structure was identified in the right lower abdomen. Gradually, the cystic mass was replaced by echogenic content and eventually attained the appearance of hyperechoic bowel. At 21.2 weeks, the anal sphincter could not be demonstrated which was consistent with the diagnosis of isolated anal agenesis. Amniocentesis revealed 46XY karyotype with normal comparative genomic hybridization. After termination of pregnancy at 23 weeks, an autopsy revealed an isolated high type anorectal malformation (ARM) without fistula. We reviewed all 14 cases reported in the literature of first trimester sonographic expression of ARM.