At autopsy of a newborn, the hydrostatic lung test (docimasia pulmonaris hydrostatica) is found to be positive (lungs float). This finding indicates that the child:

• A Was born alive and breathed, inflating the lungs with air
• B Was stillborn but had undergone post-mortem putrefaction filling lungs with gas
• C Definitively was murdered by smothering after live birth
• D Could have either breathed or undergone putrefaction — the test is unreliable in isolation ✓

Explanation

The hydrostatic lung float test (Breslau's second life test) is positive (lungs float) when air or gas is present in the alveoli. Aerated lungs float because their density falls below 1.0 g/mL. However, putrefactive gas production in a stillborn infant can also make the lungs float, giving a false-positive. Conversely, a live-born infant who died from respiratory distress may have incompletely aerated lungs that sink. The test must be interpreted in conjunction with histology (alveolar expansion, cord coiling, surfactant), putrefaction stage, gestational age, and clinical history.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.