Laboratory Tests
Common investigations Costs of blood tests Use of the blood gas machine in NICU Common investigations When filling in lab request forms - please use the name and MP number of the consultant in the unit at the time. Day 1: All sick babies need an FBC ( no differential count ) and blood culture Blood cultures should contain at least 1 ml of blood and must be done as a sterile procedure Day 2-3: U&a
Use of the blood gas machine in NICU
Common investigations
When filling in lab request forms - please use the name and MP number of the consultant in the unit at the time.
Day 1:
- All sick babies need an FBC (no differential count) and blood culture
- Blood cultures should contain at least 1 ml of blood and must be done as a sterile procedure
Day 2-3:
- U&E
- CRP (if indicated to “rule out sepsis”)
- Unless specifically indicated: no gentamicin level or repeat FBC
- Do SBR on: all D2 prems, and on jaundiced term infants
Specific situations requiring laboratory monitoring:
- Jaundiced infants:
- SBR daily while on phototherapy, more often if SBR is high and rising (see relevant section, speak to registrar /consultant)
- SBR on the day after stopping phototherapy (except for “well” term babies)
- VLBW or babies with BPD require a HB with retics, CMP, ALP and U&E on day 14 of life and this can be repeated weekly or biweekly
- Infants on TPN: weekly U&E, LFT, CMP & triglycerides
- Well babies with BW > 1500g admitted only for growth do not need blood tests on admission, an FBC, SBR and U&E can be done on day 2.
Costs of blood tests
Please consider cost implications before ordering blood tests. The neonatal unit is the largest contributor to laboratory expenses in the paediatric department. Do not send chromosomal studies or any other specialized test without discussing with a consultant first.
Use of the blood gas machine in NICU
The blood gas machine at Rahima Moosa is virtually maintenance-free, it is essential that blood specimens containing thrombus, not be inserted into the gas machine.
To avoid venous or arterial specimens being clotted:
- Pre-heparinise the syringe
- Draw the entire sample into the body of the syringe, invert the syringe 5 times and roll the syringe 5 times between your hands
- Never use a sample that you suspect may be clotted e.g. cord blood
Blood from heparinised syringes should not be submitted for culture.
The blood gas machine provides data on acid-base status, oxygenation, lactate, in addition to basic electrolytes (Na+, K+, ionized Ca2+) and haemoglobin. Therefore avoid submitting unnecessary samples to the NHLS laboratory which increases the cost of care.
Rahima Moosa Mother and Child Hospital - Neonatal Care Handbook 2023; Laboratory Tests; Common investigations, Costs of blood tests, Use of the blood gas machine in NICU
Last checked for updates: January 2024