Prenatal pelvic MRI: additional clues for assessment of urogenital obstructive anomalies.
OBJECTIVE
Ultrasound prenatal evaluation of pelvic cystic mass can be challenging. After having ruled out a cloaca anterior to a large hydrocolpos, it is important to differentiate between combined urogenital anomalies such as urogenital sinus and isolated genital anomalies.


METHODS
We reviewed the charts of 13 women referred for a third trimester pelvic MRI for cystic pelvic mass discovered in second trimester ultrasound. We evaluated MRI compared with postnatal surgical findings in order to determine clues for improving prenatal diagnoses.


RESULTS
MRI excluded the diagnosis of cloacal malformation in nine cases with no false negative. Once a cloaca is ruled out, a different signal between the bladder and the hydrocolpos on T2 sequences is in favor of an isolated genital obstruction. In contrast, in case of urogenital sinus, the vagina is filled with a mixture of genital secretions and urine, which gives it an MRI signal similar to the bladder on T2 sequences.


CONCLUSIONS
Third trimester fetal MRI is an essential exam for characterization of pelvic cystic mass diagnosed by ultrasound. This exam appears valuable for invalidating the diagnosis of cloacal malformation and for differentiating between isolated genital obstruction and urogenital sinus.
AP-HP, Hôpital Robert Debré, Service de Chirurgie Viscérale et d'Urologie Pédiatriques, centre de référence de maladies endocriniennes Rares de la Croissance, F-75019 Paris, France; Université Paris Diderot, Sorbonne Paris Cité, F-75019 Paris, France. Electronic address: carmen.capito@inserm.fr.
Carmen
C
Capito
AP-HP, Hôpital Robert Debré, Service de Radiologie Pédiatrique, Paris, France. Electronic address: nadia.belarbi@rdb.aphp.fr.
Nadia
N
Belarbi
AP-HP, Hôpital Robert Debré, Service de Chirurgie Viscérale et d'Urologie Pédiatriques, centre de référence de maladies endocriniennes Rares de la Croissance, F-75019 Paris, France. Electronic address: annabel.paye-jaouen@rdb.aphp.fr.
Annabel
A
Paye Jaouen
Université Paris Diderot, Sorbonne Paris Cité, F-75019 Paris, France; AP-HP, Hôpital Robert Debré, Service d'Endocrinologie Diabétologie Pédiatrique et Centre de Référence des Maladies Endocriniennes Rares de la Croissance, F-75019 Paris, France; Institut National de la Santé et de la Recherche Médicale Unité UMR 676, F-75019 Paris, France. Electronic address: juliane.leger@rdb.aphp.fr.
Juliane
J
Leger
Université Paris Diderot, Sorbonne Paris Cité, F-75019 Paris, France; AP-HP, Hôpital Robert Debré, Service d'Endocrinologie Diabétologie Pédiatrique et Centre de Référence des Maladies Endocriniennes Rares de la Croissance, F-75019 Paris, France; Institut National de la Santé et de la Recherche Médicale Unité UMR 676, F-75019 Paris, France. Electronic address: jean-claude.carel@rdb.aphp.fr.
Jean-Claude
JC
Carel
Université Paris Diderot, Sorbonne Paris Cité, F-75019 Paris, France; AP-HP, Hôpital Robert Debré, Service de Gynécologie, Obstétrique et Diagnostic Prénatal, F-75019 Paris, France. Electronic address: jean-francois.oury@rdb.aphp.fr.
Jean-François
JF
Oury
AP-HP, Hôpital Robert Debré, Service de Radiologie Pédiatrique, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, F-75019 Paris, France. Electronic address: guy.sebag@rdb.aphp.fr.
Guy
G
Sebag
AP-HP, Hôpital Robert Debré, Service de Chirurgie Viscérale et d'Urologie Pédiatriques, centre de référence de maladies endocriniennes Rares de la Croissance, F-75019 Paris, France; Université Paris Diderot, Sorbonne Paris Cité, F-75019 Paris, France. Electronic address: alaa.elghoneimi@rdb.aphp.fr.
Alaa
A
El-Ghoneimi
D002988:Cloaca / Q000002:abnormalities; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D016216:Ultrasonography, Prenatal; D014564:Urogenital Abnormalities / Q000000981:diagnostic imaging*
Cloacal malformation; Imperforate hymen; Prenatal imaging studies; Urogenital sinus