Third Trimester

Ultrasound scanning guidelines

Third Trimester Assess: Fetal number Fetal cardiac activity Fetal anatomy Growth parameters Fetal lie Placental localisation Liquor Cervix Maternal pelvic / adnexal massess Documentation: Transverse placenta Midline of internal os showing placental relationship Amniotic Fluid Index (AFI) Transverse chest documenting fetal heart movement with M-mode Documentation of fetal lie showing head/neck position Measurements including BPD / HC AC Femur length Trans kidneys (coronal view + renal length if dilatation present) Trans bladder Coronal diaphragm Twins Twin pregnancy scanning guidelines

Renal Dilatation If renal dilatation present The definition of renal dilatation changes at 32 weeks to: Mild >7mm but <10mm Moderate / marked >10mm

Placenta Previa Defined in the 3rd trimester as a placenta less than 5 cm from the internal os Measure and document the distance between the lower margin of the placenta and the internal os Assess lower uterine segment with colour Doppler for evidence of vessels crossing the internal os Determine the site of placental cord insertion Documentation of internal os in long midline / trans +/- clipstore with colour Doppler

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