Spontaneous resolution of an umbilical cord arteriovenous fistula
Bibliographic record
Abstract
Abstract An umbilical arteriovenous (AV) fistula is an extremely rare anomaly of the umbilical cord, with only one case being documented in the literature. The purpose of this report is to describe the prenatal sonographic characteristics of such a lesion and its potential complications. We report a case of an umbilical cord AV fistula detected at 24 weeks of gestation in one fetus of dichorionic-diamniotic twins. Color flow and spectral Doppler examinations showed a jet originating from one of the umbilical arteries entering the dilated umbilical vein. Serial ultrasounds revealed relative oligohydramnios and deep A waves in the ductus venosus for the affected twin. Upon performing fetal echocardiography assessment, mild cardiomegaly and dilatation of the inferior vena cava were detected. Chromosomal testing revealed a normal karyotype. The patient continued to be followed for close monitoring of fetal well-being and corticosteroids were administered. Cesarean section was planned for 28–30 weeks, but surprisingly, the oligohydramnios resolved, Doppler studies normalized, and no further intra-uterine growth restriction or fetal compromise was observed. Due to the recurrence of abnormal Doppler studies at 36 weeks of gestation, the patient was admitted for an induction of labor followed by a vaginal delivery of two healthy infants. Given the scarcity of reports regarding umbilical cord AV fistula, it is important to perform an extensive investigation of the affected fetus including karyotype and echocardiography. Furthermore, delivery timing should rely on close surveillance of fetal well-being to avoid the risk of fetal demise.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.008 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".