# Obstetric Ultrasound (us/obstetric)

> Trimester-aware pregnancy scan read: planes, biometry, GA, EFW, centiles, fluid and Doppler.

Upload an obstetric ultrasound study (standard-plane stills, cine loops or video from the second and third trimester). One run returns the standard plane of every frame, fetal biometry (BPD, OFD, HC, TAD, APAD, AC, FL) on the best head, abdomen and femur frames with the calipers drawn on them, gestational age by INTERGROWTH-21st and Hadlock, estimated fetal weight (Hadlock HC-AC-FL), biometry ratios and, with a dating gestational age, INTERGROWTH-21st centiles, the EFW centile and the size-for-gestational-age category. Every number traces to a caliper on a frame. A draft report is available as an opt-in add-on.

Model page: https://medrun.ai/models/us/obstetric
Status: beta · version 1.0.0 · viewer: image

## Input

Obstetric study, second or third trimester: the head (transthalamic), abdomen (AC plane) and femur stills or cine, as DICOM from the scanner (calibrated) or as PNG / JPEG / MP4 exports. Add the dating gestational age for centiles.

Accepted: DICOM files or folder, CD export (DICOMDIR), zip, PNG / JPEG stills, MP4 / MOV clips.

## Pricing

- `us/obstetric/interpret`: $0.08 per request
- Draft report (opt-in, `options.report`): +$0.02 per run

## Result sections

- `#planes` Standard planes (available): The plane of every frame (transthalamic, transventricular and transcerebellar head, AC plane, femur, thorax, maternal cervix, other) with its confidence and the key frame of each plane found.
- `#biometry` Fetal biometry (available): BPD, OFD and HC on the head plane, TAD, APAD and AC on the abdomen, FL on the femur (outer-to-outer calipers, median of up to three frames each), with the caliper overlay of every measured frame; gestational age by HC (INTERGROWTH-21st) and by HC, AC and FL (Hadlock 1984); EFW (Hadlock 1985, HC-AC-FL); cephalic index, HC/AC, FL/AC and FL/BPD.
- `#growth` Growth centiles (available): Centiles and z-scores of HC, BPD, OFD, AC and FL (INTERGROWTH-21st fetal growth standards) and of the EFW (Hadlock 1991), with the size-for-gestational-age category (SGA < 10th, AGA, LGA > 90th centile) and the ISUOG work-up recommendation for SGA.
- `#amniotic-fluid` Amniotic fluid (planned): Deepest vertical pocket and amniotic fluid index from quadrant images or a sweep; oligo- and polyhydramnios.
- `#placenta` Placenta (planned): Placental location and distance to the internal os (praevia, low-lying), accreta signs.
- `#early-pregnancy` Early pregnancy (planned): Gestational sac, yolk sac, embryo, cardiac activity, MSD and CRL; intrauterine pregnancy and viability category.
- `#nt` Nuchal translucency (planned): NT, CRL, nasal bone and plane adequacy on the 11–14-week mid-sagittal view.
- `#fetal-heart` Fetal heart screen (planned): Four-chamber, outflow-tract and three-vessel views, cardiothoracic ratio and screening flags.
- `#anomaly-screen` Anomaly screen (planned): ISUOG mid-trimester checklist completion and anomaly flags by region.
- `#cervix` Cervical length (planned): Transvaginal cervical length and funnelling.
- `#labor-progress` Labour progress (planned): Angle of progression, head–symphysis distance and head direction on transperineal images.
- `#presentation` Fetal presentation (planned): Presentation and lie, number of fetuses and cardiac activity from sweeps, including blind sweeps.
- `#doppler` Fetal Doppler (planned): Umbilical artery PI/RI and end-diastolic flow, MCA PI and PSV (MoM), CPR, uterine artery PI.
- `#report` Draft report (available): Opt-in draft report (findings, impression, limitations) written from the structured result; every number is validated against it.

## Endpoint `us/obstetric/interpret` (run)

The full read of the study: every still, cine loop and video is read, each frame gets its standard plane, and the best head, abdomen and femur frames are measured; gestational age, EFW, ratios and growth centiles follow.

Docs: https://medrun.ai/models/us/obstetric/api · OpenAPI: https://api.medrun.ai/v1/models/us/obstetric/interpret/openapi.json

### Input schema

- `files` (array; required): The obstetric study: DICOM files, a folder, a CD export or a zip, or PNG / JPEG stills and MP4 / MOV clips. `file_…` ids from /v1/uploads or https URLs.
- `clinical_context` (object): Optional. Never names, IDs or dates.
  - `age_years` (integer): Maternal age (years)
  - `sex` (string; one of female, male, other, unknown): Sex
  - `indication` (string): For example "growth scan, suspected SGA" or "routine anomaly scan".
- `options` (object): Options
  - `dating` (object): Gestational age on the day of this scan from the LMP or an earlier scan. Needed for growth centiles and the size-for-gestational-age category.
    - `ga_days` (integer; required): For example 140 for 20 weeks + 0 days.
    - `basis` (string; default "lmp"; one of lmp, crl, prior_scan, ivf): Basis
  - `mm_per_px` (number): For PNG / JPEG / MP4 exports without calibration. DICOM calibration is used when present.
  - `report` (boolean; default false): Adds a draft report written from the structured result (English). +$0.02 per run.
  - `previews` (boolean; default true): PNG of every measured frame with the calipers the numbers came from.

### Example (cURL)

```bash
response=$(curl --request POST \
  --url https://api.medrun.ai/v1/run/us/obstetric/interpret \
  --header "Authorization: Bearer $MEDRUN_KEY" \
  --header "Content-Type: application/json" \
  --data '{
  "input": {
    "files": [
      "file_01K6R4X2Q9Y7T3V5W8Z0A1B2C3"
    ],
    "options": {
      "dating": {
        "ga_days": 245,
        "basis": "lmp"
      },
      "report": false
    }
  }
}')
REQUEST_ID=$(echo "$response" | jq -r .id)
```

## Output

The MedRun result envelope: https://medrun.ai/docs/result-envelope