Validation and proposal of a clinical intervention cutoff in fetal scalp blood for the point-of care-lactate meter StatStrip^®2

Abstract

Introduction: This multicenter, prospective observational study aimed to evaluate the performance of the StatStrip^® Lactate 2 (Nova Biomedical, Waltham, US) point-of-care device for fetal blood lactate measurement and to determine the corresponding lactate value equivalent to the established intervention cutoff used with the outgoing StatStrip^® Lactate device. Material and Methods: The study was conducted from August 2024 to February 2025 at two maternity clinics in Sweden and one in Denmark. It included women with singleton pregnancies (≥35 + 0 weeks) undergoing fetal blood sampling due to non-reassuring intrapartal fetal heart rate patterns during labor. Fetal scalp blood sampling (FBS) lactate concentrations were measured using both StatStrip^® Lactate and StatStrip^® Lactate2. The first StatStrip^® Lactate measurement guided clinical decisions, while subsequent StatStrip^® Lactate2 measurements were recorded for validation and establishment of a conversion equation by linear regression. Additionally, arterial and venous umbilical cord blood samples were analyzed by both ABL 800 (Radiometer, Denmark) and StatStrip^® Lactate2 for validation. Results: Blood samples from 349 fetuses were included, with 549 parallel FBS lactate samples. StatStrip^® Lactate2 concentrations correlated with StatStrip^® Lactate (r = 0.94;p ≤ 0.001). A conversion equation was retrieved: StatStrip^® Lactate2 = (1.4 × StatStrip^® Lactate) − 0.28. From 37 paired umbilical cord blood samples, the correlation between lactate concentrations by StatStrip^® Lactate2 and ABL800 was r = 0.99 (p ≤ 0.001) in arterial blood and r = 0.98 (p ≤ 0.001) in venous blood. Mean coefficients of variation for lactate concentrations >3.0 mmol/L were 8.2% in fetal scalp blood and 3.8% in umbilical cord blood. Conclusions: A fetal blood lactate concentration ≥7.0 mmol/L measured by StatStrip^®Lactate2 corresponds to the established intervention cutoff lactate value ≥5.2 mmol/L measured by StatStrip^®Lactate. Precision was acceptable but may be improved by using the mean of two measurements, particularly when the first result falls between 6.0 and 8.0 mmol/L. We also recommend ensuring the correct sampling techniques to minimize preanalytical variation.

Abstract (Swedish)

Introduction
This multicenter, prospective observational study aimed to evaluate the performance of the StatStrip® Lactate 2 (Nova Biomedical, Waltham, US) point-of-care device for fetal blood lactate measurement and to determine the corresponding lactate value equivalent to the established intervention cutoff used with the outgoing StatStrip® Lactate device.

Material and Methods
The study was conducted from August 2024 to February 2025 at two maternity clinics in Sweden and one in Denmark. It included women with singleton pregnancies (≥35 + 0 weeks) undergoing fetal blood sampling due to non-reassuring intrapartal fetal heart rate patterns during labor. Fetal scalp blood sampling (FBS) lactate concentrations were measured using both StatStrip® Lactate and StatStrip® Lactate2. The first StatStrip® Lactate measurement guided clinical decisions, while subsequent StatStrip® Lactate2 measurements were recorded for validation and establishment of a conversion equation by linear regression. Additionally, arterial and venous umbilical cord blood samples were analyzed by both ABL 800 (Radiometer, Denmark) and StatStrip® Lactate2 for validation.

Results
Blood samples from 349 fetuses were included, with 549 parallel FBS lactate samples. StatStrip® Lactate2 concentrations correlated with StatStrip® Lactate (r = 0.94;p ≤ 0.001). A conversion equation was retrieved: StatStrip® Lactate2 = (1.4 × StatStrip® Lactate) − 0.28. From 37 paired umbilical cord blood samples, the correlation between lactate concentrations by StatStrip® Lactate2 and ABL800 was r = 0.99 (p ≤ 0.001) in arterial blood and r = 0.98 (p ≤ 0.001) in venous blood. Mean coefficients of variation for lactate concentrations >3.0 mmol/L were 8.2% in fetal scalp blood and 3.8% in umbilical cord blood.

Conclusions
A fetal blood lactate concentration ≥7.0 mmol/L measured by StatStrip®Lactate2 corresponds to the established intervention cutoff lactate value ≥5.2 mmol/L measured by StatStrip®Lactate. Precision was acceptable but may be improved by using the mean of two measurements, particularly when the first result falls between 6.0 and 8.0 mmol/L. We also recommend ensuring the correct sampling techniques to minimize preanalytical variation.

• author: Gellert, Sofie ; Norrestam, Sara ; Tidstedt, Alexandra ; Ignell, Claes ; Isberg, Per Erik ; Wiberg, Nana and Iorizzo, Linda
• organization: Clinical Sciences, Helsingborg; Department of Statistics; Obstetric, Gynaecological and Prenatal Ultrasound Research (research group); Valid IntraPartum Surveillance and Interventions to make Pregnancy Safe (research group); Obstetrics and Gynaecology (Lund)
• publishing date: 2025-10-26
• type: Contribution to journal
• publication status: published
• subject: Gynaecology, Obstetrics and Reproductive Medicine
• keywords: acidosis, fetal blood, fetal monitoring, lactic acid, point-of-care testing
• in: Acta Obstetricia et Gynecologica Scandinavica
• volume: 104
• issue: 12
• pages: 2273 - 2281
• publisher: Wiley-Blackwell
• external identifiers: pmid:41139852; scopus:105019972636
• ISSN: 0001-6349
• DOI: 10.1111/aogs.70080
• language: English
• LU publication?: yes
• additional info: Publisher Copyright: © 2025 The Author(s). Acta Obstetricia et Gynecologica Scandinavica published by John Wiley & Sons Ltd on behalf of Nordic Federation of Societies of Obstetrics and Gynecology (NFOG).
• id: 02528a35-8042-4ca8-851f-e3d6b9082733
• date added to LUP: 2025-11-25 11:54:18
• date last changed: 2025-12-19 16:18:36