Objective To summarize the management and analyze the causes for intracavitary ECG-guided implantation failure of upper arm infusion ports, and to propose proactive nursing strategies. Methods In 4 cases of gynecological tumor patients undergoing infusion port implantation, intracavitary ECG was used for tip positioning. Two cases showed characteristic high and sharp P waves during the procedure, one case showed an increase in P wave amplitude, and one case showed unchanged P wave amplitude. Post-insertion chest X-ray imaging revealed misplaced catheter tips in all cases. The catheters were pulled back based on chest X-ray results or the characteristics of intracavitary ECG P waves. A slew of methods, including saline flushing, internal jugular vein blockade, pulled back of the guide wire, and coordinated breathing, were used for catheter repositioning. Results Successful catheter repositioning was achieved in the 4 cases. Conclusion Improper catheter reinsertion after guide wire pulled back, failure to effectively identify abnormal changes in intracavitary ECG P waves were the main reasons for IC-ECG guided implantation failure. During intracavitary ECG-guided tip positioning, medical staff should keep a close eye on P-wave amplitude and morphology to guard against catheter bending or misplacement.